If you want to try it out first it's a better idea to rent, that way you get something that's at least decent. (Rentals are usually private between two members so ask around on your local forums, price should be $20-40, owner sets the price to rent so shop around for different members to see what they have to offer). In addition to rental theres field fees (usually ~$10-20), BB's ($15-20 for a bag of 2000), and you should pick up some BDU's (Surplus Olive Drab from most surplus stores should cost around $40-60 for the set depending on condition and such). For indoor games it's not as big of a deal (I haven't played many indoor games so I'm not too experienced with this) however for outdoor games it's advised to buy BDU's just to "get into the mood", you'll blend in more rather than having a hoodie and jeans (because it's too easily seen from a distance), and you'll be more respected since you actually made an effort to try and join the group on the right foot (that is you actually bought some stuff, albeit it's minimal but it kind of shows that you came prepared and can take care of yourself and don't need another member to hold your hand).
Also, sure you could play with a $200 gun but it's like the difference between a Weekend Warrior and a car made exclusively for the track. The $100 guns you get at Canadian Tire are more akin to crappy daily drivers (like a rust bucket you would buy in university to get from A to B and you pray every time you start/drive it, it doesn't break down/explode/fall apart) that are only good for plinking in the basement.
It's best to start off with a quality gun right off the bat and if you're going to "try it out" to see if you like it a high quality gun actually holds it value REALLY well. Whereas if you buy a crappier gun (Kraken or something) then the value depreciates rapidly since most members will try to stay away from them.
EDIT: As for the BB piercing thing. Usually they won't, the big areas are usually teeth, ears and soft parts of your body. Pinky shots hurt like a bitch but won't pierce.
Remember you only get one set of eyes so good eye protection is manditory, sure you could get that set of goggles that are properly rated but seem like they were made shoddily OR you could get a nice set of $50-100 goggles that will protect your eyes forever.
As for teeth, a bandanna will usually reduce the energy enough that it doesn't chip however what I do is run with a Sykes mask (Version 1) (bought from Illusion) http://www.sykesmasks.co.uk/images/Tan%20Black.jpg
I didn't buy the goggles that came with it I use my own. Other people have used neoprene masks to great effect too (ones that bikers or boarders/skiers would wear). From worst protection to best I would say Bandanna (something like this
is pretty badass and can give you that badass PMC look, you should be able to buy these from motorcycle shops or whatever) second is those neoprene masks like this
which is also pretty badass, again you can pick them up from motorcycle shops or whatever), and finally the Sykes mask (I don't know what it's made of, my guess is some sort of fibreglass/resin mixture) It's extremely hard and I think I read somewhere it can withstand shots of up to 800 FPS (twice what the regular field limits in Canada are). It actually saved me once, I took a shot to the face just to the right and below the bridge of my nose, if I didn't have that mask it probably would have been a bleeder.
Remember to tuck in your ears into the elastic of your goggles. Otherwise a stray BB can give you a bleeder there too.
I've also seen someone with a BB embedded here in Canada (you could still see it and all that was required was picking it out). It was a guy from Vancouver IIRC however I'm sure it was a freak accident.