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..
Darkweb is the biggest marketplace of internet and you could buy anything you want by paying cryptos. Also use market place section of bitcointalk as temporary solution in case if you need it.