St Joseph, MI
Seems like one important question here is if you are a retail business seller or just some guy.
If you are just some guy who sells a pin from his collection here and there, I think the service expectation is much lower.
If you are operating a business the service expectation is higher.
It sounds to me like you have been very fair so far either way.
As for your question on Xenon, has the buyer asked for reimbursement? I probably would not expect any, but that's just me.
Just be clear about future issues with the buyers at the sale, and stick with whatever you say. You can have any policy you want as long as it is clear, and you keep any commitment you make.
