I bought a TNM500 on eBay for $400 with 15 adaptors after a good bit of discussion on EEVblog. I have tried it once to read a PC BIOS chip which it seemed to do fine once I figured out the UI. TNM is actually an Iranian company which rather surprised me. The unit itself came from China.
It seems to have good device support. I was quite underwhelmed by both the TL866 and the GQ documentation.
I chose the TNM for the simple reason the cost started going up very steeply from there. I purchased it primarily for the same reason, to be able to copy old T&M gear devices. But I also destroyed the NAND flash in an Instek DSO by accident, so I needed something that would program that. The EEVblog thread reported lots of issues with the TL866 variants as well as the GQ versions.
