My cheap version: Pallets, bricks, and some kind of flooring on top.

Lay down your wooden pallets. Put bricks in them (two lines, middle of each side of the pallet), both to support the boards when weight is put on them, and to weigh down the pallets. Then put some sort of flooring on top (I like rubber mats, but linoleum works), making it easier to clean and easier on the feet. Put some bricks on top of the flooring, too, to keep it from floating away.