Obfuscate and Prosper?

Ebay confuse me. Throughout my recent creation of a listing for an as-new RME Fireface UC I was told my ebay costs would come to 37 euro. When I received payment, said amount was deducted from me by PayPal. All appeared to be well.

This morning, about two weeks after that sale, I was surprised to find a ‘monthly invoice’ from Ebay for 67 euro in my inbox. Pardon me?

If this was some fee that’s standard on making a sale, Ebay managed very well, through their listing UI, to ensure I was not aware that I would be liable for this amount.

As far as I can tell that means my cost of selling the item on E.bay has been approx 15%. Which feel like a lot to me.