This forum, plus HBAS members (if you join), are great places for cheap fish and plants.
I much prefer live to plastic and the tank will be easier to look after in my opinion (sorry, I guess I should have said IMO 8) ) as they help the tank keep a nice nutrient (not sure if that is the right word) balance.
I would go for a shoaling species like the barbs, rummy nose tetras, harlequins, rasboras etc. They are always on the move.
Lighting need not be expensive either. Basic fluorescents will do the job