$200 seems kinda steep. Why not just use a milk crate?
[img]http://us.st11.yimg.com/us.st.yimg.com/I/cinemasupplies_1941_4835362[/img]

If you really want something hitch-mounted, go with a cargo carrier you could use for more than just a step. They start around $50, but I got mine on sale at Harbor Freight fo $30.