I haven’t been selling on Ebay for 20 years, but last time commissions were only about 2.5% back then I think plus 1% over a set amount
even at 13%. That’s only $97.50 so you would still get $650. That’s if it reaches that price. Now they charge a percentage if you place a reserve on it.
most forums require a minimum number of posts to weed out scammers now
Ebay could be your best bet. If you place a $600 value on the reserve. Take a chance and maybe it goes higher. If it doesn’t sell. Ask a bit more from the person that offered $500