Ebay pricing isn't an exact science, especially when discussing empegs which come in differing capacities. It is very dependant on how many others are being being offered (Supply) and how many people are looking for them (Demand), neither of which can be accurately gauged.

Now your empeg is an interesting case - you connector problem probably wouldn't put off many of the more technical people here, but may be off putting to people who aren't aware that it is fairly easy to rectify.

But if I were posting it on ebay at the moment, I'd probably set a declared reserve of $500, and a Buy It Now of $750.