Well, it appears that my 30-year love-hate relationship with Volvo is finally over (for now). We just traded in the wife's '96 850 wagon on a new Prius. Since the Toyota folks didn't seem to care too much about our trade one way or the other, I pulled out the nearly new 6-disk changer before the trade.
I bought the changer new from Volvo three years ago for $300. I believe that it's made by Alpine and fits most Volvos with the factory wiring and head unit 1995-2000 or so. I thought I'd try to sell it here before resorting to Ebay.
$75 + shipping. including original packaging and one empty cartridge. Note that your Volvo must be pre-wired for it (ours was).