Long story short, I bought this to use with MAME on my modded Xbox but found out after I got it that there's no mouse support (just in Xbox MAME. Works fine in PC MAME). It's new & unused and I've never taken it out of the box. Even have the original X-Arcade shipping box for it. I did cut the UPC out on the box for the rebate though.
Asking $70 + shipping. Sold for $99 on the X-Arcade site but it looks like they don't make them any more. Built like a tank and has a lifetime warranty. Has buttons on the L & R sides, so it can also double as a PinMAME controller. Comes with a cd-rom of 12 Atari arcade games too.
IGN review: http://gear.ign.com/articles/685/685507p1.html