we just got really cheap stairs from target for $20. No 'real' assembly required, just snap some stuff in place and place this furry cover over it. They're about a foot tall. Before I bought the stairs, I just used Peekaboo's old cage/crate thing with a blanket covering it, for him to jump up on.
http://www.target.com/gp/detail.html...sin=B000E8HQ9Q
Target users gave it good ratings too lol.