most people use the 0.8L 4500psi fibre wrap ones, cost about £125 new :S may be out of your price range (im currently saving up for one now) haha.
steel is weighty, 0.8 3000psi tank will nearly weigh as much as a 1.1 fibre tank (with cover... and alot of muck and dirt
) as i currently have both.
if youv got arms of steel (hehe, c wot i did there) then go for the 1.1 steel, may regret it in the long run, fill stations are at hand most of the time, so small tanks work dandy imo.
I'd be happy to sell you my 0.8 steel air tank for around £35inc p&p if your intrested