What's a good standard to use when offering or buying bike parts? Say for example a LHS foot peg hanger new cost $110 from Motobins. Would it be reasonable to pay 50%, 30% ... for one from a broken or scrapped bike?

I guess one would adjust the percentage down for minor damage-but-still-okay like a dent in a fuel tank.

hard to figure whats a good price ...but consider this

if one was to purchase a cheep but non functioning bike ...lets say $500 all up

what are the individual parts worth as a portion of the sales return ...for some that might make a tank worth only $60 ...so not an easy or fair calculation can be easily realised ..
but if its a common faulted part ...but no longer available ...this could distort the real value ?
just some thoughts

I guess they have to be condition related, new 100% 2nd hand 50% as good as new 75% and old poor condition 25% or less, perhaps mates rates would apply.