Yeah, the gym is above the climbing wall...not actually been in there though...too lazy.
For full membership for a year it's something like £130, for basic it's £80...I think, can't fully remember the pricing.
Purbeck is good for sociable and for not so sociable people due to the fact you are in a flat of 5 (some are 6) people, so you socialise with them, but you have 4 flats per floor, and there are often large groups of people that go out together, especially at the start of term.
You get things like pub crawls etc. organised by the staff at Purbeck to help you socialise. I certainly had great fun there, I'm not one to be clubbing every night and neither were my flatmates, which was good, if I'd ended up with people that always went clubbing I'd have gotten annoyed.
Inferno is the local SU owned pub in Bournemouth, due to the two campuses there is Inferno on Lansdown and Dylans on Talbot. The Firestation is also SU owned and so runs loads of SU organised events, which is good.
All of the local pubs and clubs are good (that I've been to anyway), but avoid FYEO, and go to Wiggle at least once.
For prices of drinks etc. just don't go out on Fri/Sat nights to the main bars and clubs in town as it's non student nights so they charge silly amounts for everything. Mon-Thurs nights are all student nights so there are loads of places that have offers on drinks and things so you can get merry and have fun.
InvG