I'm sick of the fees on Ebay it's become totally unprofitable for some items due to the massive fees. I use Facebook marketplace but that's more for local sales.
With crypto Ebay you could have near zero fees and have a decentralized marketplace model. I know there are things on TOR etc, but I just wouldn't trust it tbh..
Why do you think that you could have near zero fees? Do you really think that marketplace won't set fees despite the fact that it uses cryptocurrencies? Marketplace is looking for profit, check how much profit does ebay makes and then you'll understand Ebay loves billions, green billions.
Crypto version of Ebay will be very hard to create and will require enormous amount of money. You have to attract buyers/sellers, increase demand/traffic, hire developers, customer supports, project managers and etc. Crypto doesn't have that much demand and one similar step from Ebay means your business is most likely gone. So, believe me, there won't be serious crypto analogue of Ebay, at least right now. In future, I don't know.