I want/need this model of computer badly. Can't find any on Amazon or eBay, they seem ultra-rare. What sort of asking price should I expect?
Are there any online specialist shops which deal in retro PCs?
The IBM 5100 was the one with APL on it, wasn't it? Pretty much all of these computers are going to be locked up in collections by serious computer collectors, because IBM didn't make many of them - probably out of fear of damaging their then-burgeoning mainframe and minicomputer sales. Then there's the fact that they cost at least $9,000 when new, and consider inflation into account...
You'll be lucky to find one at all, and if you do, they'll be expensive, like several thousands of dollars at least. As you have already surmised, they are ultra-rare, and I don't even know if there are any emulator projects for the IBM 5100 hardware. I think you'd be dealing one-to-one with a serious retrocomputing enthusiast if you were in the market for one.
IBM 5100 can cost 32K, if you can find one. I've been looking for one for a while to.
El Psy Congroo
i used to have an IBM 5100 but then i lost my penis