I made an error recently with a Ebay purchase.
I bid on a VN Turbo 700 gearbox crossmember. But because i read through the add to fast i misread it thinking it was to suit a HZ.
I only bid $5 and won.
Once i realised i messaged the seller of my error, found out the add cost (and fee) and sent him the $$.
Even though he didn't sell it, he was happy that he didn't lose any $$ because of my mistake.

But that's just me!!