Vintage T-Shirt Forum & Community Authentication Appraisals

Hello, I’m just hoping to get a bit more info on what this is worth. So far I found one go on Grailed for round $60 but I cannot find any others anywhere. I’ve found Reddit threads recently claiming these are worth hundreds and I’ve had an offer of 350. So far it’s all over the place and I’m hoping to get more info.

I can't find any evidence in past eBay sales for it - so perhaps it's being dealt privately, but if the same shirt is $60 online why would the person offer you $350?