Buying an "untested" or "not working" KI / KI2 board is an interesting gamble, and having bought many in my time, I've found that there IS a very real science to it:
Rule 1)
If the seller is someone who buys and sells arcade stuff for a living, and they call it untested, that is a lie. It's tested alright, and it's dead, 99 percent of the time it's a blown surface mount CPU, that's gonna cost about as much to repair as it's worth. PASS on this at any asking price over $10 (scrap cost for EPROMs).
Rule 2 )
If the seller is, to your satisfaction, someone who is purely a hobbyist who does not know how to debug/repair PCBs, this may be a working board with a dead HD. Be sure to get pictures. You are looking to be sure all the original EPROMs are populated on the board, that the heat sink is not missing/melted off the CPU, and in the case of a KI1 board running KI2 roms, that the Ki1-Ki2 daughtercard is installed. (Actually, the presence of this card now makes the board worth $50 in scrap alone for that card). Most importantly, look to see if the drive is the original, ugly drive in the plastic enclosure. If so, I'd say it's about an 80% chance the board is good and the drive is bad, and the other 20% of the time the board is dead, and again, virtually all dead KI boards are not easy, do-it-yourself repairs unless you have a high-end surface mount component reworking station and a source for very hard to find parts; so here, you're taking an 80/20 gamble for a good deal, which mathematically (to borrow the math from poker) is at about $1-$100 or so (keep in mind you will need to invest about $15-20 in parts to put a compact flash card on that board!)