surplus stores are our friends. Cheap, effective... Did I mention cheap? Look through their camo styles, try and pick something that will go well with the terrain you intend to play in. If your not really sure, go with something generic like woodland or tigerstripe, or, obviously if you live in a desert/sandy area, maybe go desert... Just use commone sense. If you can match a vest to the bdu's, do it, maybe see what vests they have first and pick a bdu style accordingly, again trying to somewhat match to your terrain. Boots are definately the most important part. Mismatch the bdus and vest if you have to to save money for some nice boots.
I advise getting something that has some decent ankle support. Remember when your tryin boots on they will all feel pretty stiff, but they will break in with a little wear, ideal support for non-broken in boots (imo) will feel like your ankle is encased pretty tightly, and you wont be able to bend your foot easily.
Also think about pickin up a pair of gloves, You don't need anything heavy duty, biking gloves even work fine, fingerless is nice (imo) but just somethin to protect teh palms and packs of your hands, nothing worse than placing your palm on teh ground to support yourself when you crawl and impaling your self on somthing, or crushing some type of thistle that leaves your hand burning and itching for the day. A bit of leather or material in between often will prevent that.
If your using a full face mask to play, or if your just using goggles, you may want to consider a baliclava or some kind of head wrap, especially if there are blood sucking bugs in your area
. Even a thin polypropelene one will do fine, very breathable, and does a nice job of reducing bites.
If your going to be playing in areas with water/swamps, may want to consider: a) waterproof boots and/or b) waterproof over socks.
yea that's all I can think of atm.