These are my favorites. They fold up and have a handle also. The seller "foryourpets" is very good. So was shipping time. They have different heights also.
http://cgi.ebay.com/NEW-24-Exercise-...QQcmdZViewItem
Forgot to say I put a piece of linoleum underneath it.
Found this too, but never ordered anything from them...
http://cgi.ebay.com/177-LARGE-Dog-FE...QQcmdZViewItem