I've been looking into picking up an early SF champ (or vibro-champ) and have been monitoring quite a few on ebay for the past couple months or so. I can't seem to figure out the reasons for the huge range in price that they seem to be going for. I've seen the same amps, more or less, (stock, same year, same condition) go from $225 - $540. I can't figure out why theses prices are all over the place. At any time there are about 10 - 20 of these amps listed so it's not like they're hard to find. The only thing that seems to be common with some of the higher priced ones is that the seller is willing to ship internationally, but even so, i've seen domestic ones go just as high from time to time. Any thoughts?