It all depends on your budget and if you want to buy new or second hand and ofcourse if your playin woodsball or tourny.
If you are on a low budget as you say then look no furthur than the for sale threads on here, you can pick up some very good kit at good prices.
Buying new you can check out the following depending again on your budget.
Online
http://www.corruptedpb.com/shop.asp?offers=1 Planet Eclipse Gear
http://www.planeteclipse.com/ Planet Eclipse Gear
http://www.lpspaintball.biz/cart.html Various Brands
http://www.bzpaintball.co.uk/ Various Brands
All excellent.
LIPs / Planet and BZ have retail shops also depending on your location.
Kit Wise you will always want to look at getting a decent mask for your first purchase. Prices range from £40 to £70 NEW
Best to try some different ones on because everyone has different views but go for a JT Proflex, E Vents,Grillz or one of the Dye masks and you wont go wrong.
Jerseys/Pants/Elbow Pads/Knee Pads again are all down to your own preference and most people get the kit that matches there marker if you know what I mean. Prices can range from £15 second hand to £98 new for pants with jerseys and pads being £15/£20 second hand to £35 New.
Other kit you will need is a HPA Tank 3000Psi or 4500Psi and a loader/hopper.
Halo loaders are a good budget buy or for a little more second hand you good buy a Vlocity for £45.
Air Tanks range from Budget steels ones to Fibre Wrapped ones at £100+ (Which are alot lighter).
Can't really give you advise on which marker to get because I have only used Ego's which are awesome markers but maybe outside your price range.
I went through all this what should I get newbie stuff when I first started in June 2008. PM me if you want to know anything else.