ZX80 - was: SN76477N

I had a go at hooking the thing up today. Tip is indeed +, and a 500 ma supply seems to be adequate. Modulator output is on channel 2 (a really strange choice for the USA, as 3 or 4 is more customary). It runs a few simple programs, but I'm not overly patient with the miserable display (particularly on a color set) and the funny keyboard. So I guess it works. This thing seems to be made in the same way that the Sinclair LED wristwatch I once had was--CHEAP is the biggest consideration. Overall, it's in very good condition, with a "33" scrawled on the bottom in orange magic marker. Usually discoloration from age on the case from age and the tip of the front (operator's) left corner of the case is upturned slightly, probably from storage. Perhaps with a little heat, it can be coaxed flat, but I'm not going to try. So what's a fair asking price for this thing? All I've got is the BASIC book and the ZX80 itself. I really don't want to eBay it. Cheers, Chuck