As with many other winter sports, getting all the equipment and paraphernalia can be expensive. Especially if you're just trying it out. So what equipment do you really need, what can you hire, and what should you look out for?
Obviously, you can't snowboard if you don't have a snowboard. But don't buy one straight away, rent one at the start to try out different types of board, and different bindings. If it's a decent rental outfit then the boards will be well serviced too, which is another thing less to worry about. After you've had a bit of experience then you can look at buying one, and then by that time you won't need to buy a beginner's board!
For board types, you'll probably want a freeride board or an all-mountain board, which are general all-purpose boards. For lighter, more flexible boards for the halfpipe, look for "freestyle" boards, and for racing look for the "alpine" or carving boards. There are also special boards for deep powder, with a wide nose and a swallow tail, but how often will you be able to use one of those? In general a freeride board will be quite happy going over jumps as well as going at speed on the piste.
There are also a few different types of bindings, from the simpler, more conventional strap-in bindings to the step-in systems and Flow systems. The race boards generally have hard boots and so different bindings too. There is no "best" kind of binding though, just go with personal preference.
Another thing to realize when you start out is that you need to decide whether you want to board with your right foot forward or your left foot forward. Usually you can find out which is your preference by sliding around the house in your socks, or skidding on a patch of ice. Once you know which is your front foot, you can set up the bindings accordingly. Of course you can always change it round if it doesn't feel natural, and you can change the angles to make your feet point more or less forward until it's comfortable.
Again you don't have to buy these straight away, and can rent them along with the board. When you do want to buy boots, it's a good idea to make sure they fit the bindings and the board properly - buying them together with the board is expensive but you can make sure it fits together (and you may be able to wangle a discount!).
You can use hard boots (like ski boots) for snowboarding, but don't, at least not at first. It's so much more comfortable with soft boots. Of course, if you're stuck with a board with hard-boot bindings, then you'll need to use hard boots with them, but really, you should use soft boots unless you're racing.
You will need gloves, preferably special snowboarding gloves, and it's probably better to buy these than rent them. Look for strong gloves which can stand a good bashing, rather than thin ones which will get waterlogged and cold. Bear in mind that with snowboarding, the gloves get much more of a battering than with skiing - they're often in contact with the snow when you're getting up, get wear when doing up and undoing the bindings, and often have to scrape snow from the back binding. So look for reinforced or rubberized fingertips and long cuffs (to stop the snow getting in). It can be useful to have removeable inner gloves too, to keep the hands warm when you take the outer gloves off and also to make drying out easier. If it's warm in the summer you can just wear the inner gloves so you don't get too warm.
Many snowboarders start out with normal hats and sunglasses, wary of the extra expense of helmet and goggles. But eventually a helmet becomes a sensible investment in protection, and many helmets don't allow sunglasses to be worn comfortably (depending on how much room there is inside). So often helmet and goggles are bought together, again to make sure they fit together properly. Helmets aren't just useful for protection against falls, there are also accidents caused by other skiers/boarders to consider, and they can even come in handy while you're stationary - mine protected me from falling snow last week and has had countless knocks from skis and ski sticks in the lift queues and in cable cars.
You shouldn't have to buy a whole new set of clothes for snowboarding - just use a layered approach as with any other winter activity and make sure your jacket and trousers are waterproof. Don't wear a woolly jumper because it'll just collect snow and get heavy and wet. The jacket doesn't have to be anything special but it helps to have snowboarding trousers, they're a bit tougher than skiing trousers and more able to stand up to the rolling around on the floor, sitting down on the snow, and that kind of thing.
Some places insist on snowboards being attached by a leash to the boarder's leg, but I think this is pretty rare now. Certainly the front foot isn't going to come out of the binding accidentally so under normal circumstances it's impossible for the board to go running away on its own anyway. And if you take your front foot out of the binding then you can be just as careful with it as when you take your leash off, so I really don't see the point of them. But in order to conform to the rules, you can get a short mini-leash which is attached to the front binding, which can clip on to a normal keyring ring on the front boot. So there's no bulky strap around the calf, just a short rope to the boot, much more practical.
A "stomp pad" is a grippy accessory which you can stick on to your board just in front of the back binding - almost all boards come with one already but they're often inadequate. A decent, spiky one makes scooting and drag-lift-riding much more controllable and they're really cheap.
Some people like to wear a rucksack when boarding to hold the supplies like sandwiches, camera, drinks and so on. I find it too bulky though and it's a pain to have to take it off for the chairlifts. What I do need with me though is a small drinks bottle and small chocolates, and they can just go in the jacket pockets.
Many ski resorts have the hands-free cards now, but they're overrated - either they don't register with the machine without you rubbing yourself up and down the sensor, or your ticket from last week registers too and it doesn't let you through. And I especially hate it when the resorts make you buy these hands-free tickets even if you'd prefer a paper one.
The paper tickets which you slot into the machine are very reliable and always work, it's just a pain if you have to get them out of a pocket first and it's uncomfortable to have them round the neck (plus they might fly off!). So a good investment is a little plastic ticket holder which is attached firmly to your jacket, and clips onto the paper ticket with a short spring-loaded string. Even without taking your gloves off it makes it really easy to poke the ticket into the machine and you're through.
The latest accessory in the armoury of the daredevil snowboarder is the back protector or Panzerrücken. It's like a plastic armadillo armour which covers your back like moto-cross armour, and is bizarrely expensive. I think it's most useful for those who play around on the metal rails or between the rocks, because I can't see many ways where you can injure your back that badly through normal snowboarding. It looks like it protects you from impacts, like if you fall on something hard and sharp, but I try not to go snowboarding where there are hard sharp objects around. Some people like having them though.
What would be much more useful, especially for beginners, is extra protection on the really sensitive parts of the body - like the wrists, the knees and the bum. All these get a bruising when falling, so learners would be well-advised to pad or protect those areas. Many snowboarding gloves have wrist protection built-in, but you can use any kind of soft knee pads inside your snowboard trousers and you can even make your own bum pad out of foam or a sleeping mat, and that will really pay dividends.