Welcome to HAN, first off.. :cheers:

If you don't mind my asking, where are you located?
(I ask because it makes a difference in market prices; I'm going to assume you're on the west coast of the US.)

DB8s (the chassis code for a GSR sedan) were pretty rare in general, certainly in comparison to the DC2 (their two-door brethren). As such, they tend to hold a bit of a price premium, assuming they're in good shape.

But the issues you've mentioned will cost a bit to repair properly.

Given that you'd need to replace the door lock assembly on the passenger front door and the need to re-spray the trunk, I would offer $6500, assuming the owner has records to document all the maintenance done to the car and that there is no rust.

Check the trunk & rear wheel-wells carefully, because there is the possibility for the sunroof drain tubes to get plugged and spill into the spare-tire well.

Lastly, if the seller doesn't have maintenance records to back up what he says he's done, I advocate walking away. Regular maintenance is crucial to a long trouble-free life with a Honda. IMHO, if the seller can't be bothered to keep a file of reciepts, I have serious doubts about he or she may have really treated the car. :a:

So, assuming the car checks out and records are on-hand, start at $6500 and see what happens.