I've been watching ebay for amiga items for 5 years, I've seen an X-Calibur only once, and then it sold for nearly as much as a 060 accelerator.
Really? How much did the '060 go for? I pick one up on ebay a year or so ago. Thought I'd be in a bidding war, got it at the starting bid of $75.00 US. Would gladly trade it for an '060. Was going to install it in my A3000T. That is untill the A3000T green screened and has been setting in pieces on the work bench. The instructions for installation of the X-Calibur are a bit extensive and requires some cutting an soldering. Be careful when buying 3640s. They will need repair.