Like others that post here, I was amazed to see an HP67 MIB going for $1500+. I'll admit, I've been known to pay top dollar for a particular example when it is needed and I wanted to end the hassle of the search & evaluation process. But I have noticed a trend of increasing prices on ebay over the years. 2 years ago I bought a MIB 67 for $450, 4 years ago it was a MIB 65 for $300. So we're looking at..what.. an exponential price curve?
I think it may be what are called "late adopters" of ebay. As with other technological trends, this group tends to have more money than brains. This is not necessarily a bad thing (especially as seen from the seller's viewpoint!).
-John