to be honest: because they're not really jdm or "sports car" rims, not too much (at least not around here). because they fit fords almost 100% easy (not commos, IIRC they're 5x120, and skyline/falcon are 5x114.3), you'd def get much better price on there. how much were they new? how old? any gutter rash? selling with tyres? which brand, what size, what wear?
allllll factors to think about. but yeah as i said above, size/offset and tyre size/brand/wear.