I bought silver with crypto before. had no problem with transaction, but for normal price. you try to make a lot by offering something which can be cheaper while paid by crypto not fiat. try charge 32 per coin to achieve 27 on eBay. I bet u will not find to many buyers. if I can pay 22+vat  with fiat why should I choose to pay 28 with crypto. if u want crypto don't charge VAT like with fiat. I do understand that u don't want sell below what paid. but this is not eBay where to anything u have to ad 10% for eBay and 2.9% for PayPal.