just get the $20 Gamestop special (forgot the name brand), then get a piece of plywood that will fit under it and cover it with slightly overlapping durable plastic mat (usually you can get them in a rool, just cut sections and cover the mat) and staple it down on the sides.
It's cheap and should work good, but you may still want something better.
If you have a lot of extra money to burn, get a Cobalt Flux board. Hand made in America i think, and is even made out of steel. It's an awsome board, but costs somewhere around $300 or so. If you get a 2xCobalt Flux combo kit tho you save some money and get a railing for free!
http://www.cobaltflux.com/products_cobalt.htm
My friend has one, it's awsome, but like i said, expensive. Get it if you're really serious about DDR. They even ran one over with a Ford Explorer and it still worked, so unless you weigh more than that you should be fine!!