Worth pennies nowadays. You can pick up XDA II's of the same age for £15 lol. Even my HTC Universal, which is a very unique specced, stupidly expensive when new and very rare handset, is only worth about £120 nowadays, and that is considered to have held its value extremely well compared to other PDA come mobile phone devices.
Its amazing how these type of things can cost hundreds new, but lose value so quickly. Thy do far more than the average "smart-phone"or even iPhone ever will, and are far more powerful, but people just do not seem to want them. I guess its just geeks or people who need them for business like me, who are happy to have the massive bulge and weight in their pockets.