It's worth investing in a few bits like gloves and socks before you go though, you can pick them up cheap enough. Get the expensive stuff like trousers, jacket and boots from the hire shops.
I'd agree - buy the cheap things that you'll get use out of for other activities. You probably only need 2 pairs of socks as you can always wash them while you're out there - or stick em out the window for a bit of an airing

2 pairs? For a weekend or week? c'mon!! What about at least one for every day to keep your feet fresh and clean? Theres not a lot of effort in loooking after your personal hygiene...lol