Totally get it. My buddy Jason and I have this conversation at least once a month.
Let's face it, we're getting old.
When my '73 Z sold for $53k, there were people freaking out, saying it was 10x what it's 'worth,' and generally whining and complaining.
The reality is, the S-chassis are a collectible commodity, and we can b**** about it until we're blue in the face...
The value of anything is [I've said this way too many times] EXACTLY, to the penny, what someone just paid for it. Not 'asking price', not KBB, not some clown on the internet's opinion. It's worth whatever it just sold for.
So, throw some offers out there. Let's be cautious not to use the word "fair." I want top dollar for my car, and you want to get it for a dollar. Somewhere in the middle is a price we can agree on. You just have to find that number.
If someone wants $6500 for their clapped-out S14, maybe it'll sit for a month. That's when you pop in with your $3k offer and explain, professionally, that if it were worth $6500, it'd be sold already.
Ultimately, you have to be able to smile, say thanks, and walk away - Sellers are often just as clueless as buyers.