'yep I got charged £2.70 to post a trading card that sold for £9 an 87p stamp is all I needed...'

------------------------------------------------------------------------------------------------------------

That should have been exempt from Stupid Delivery :

Items that are under 100gms, fit in a normal envelope and sell for under a tenner, should be able to be posted however you like 😊

Next time you list similar, look for 'custom postage'/'advanced options' etc.  (it might take a bit of finding and ebay may keep trying to push you to S.D. but have patience, you should find it!)