A friend/ work colleague/ relative offers you something they make as a hobby, when you are having a relevant conversation or completely randomly. (cake/jam/curtains/ Christmas decoration/ painting because you are organising a party/redecorating/preparing Christmas/talking about shopping). You very nicely decline. They insist, you decline again. A couple of days later, they offer again, and you decline AGAIN, very nicely. A couple of days later, they bring you the damn thing, made specially for you. You grit your teeth, thank them whilst thinking I don't want your crap, and now I have to refund you for the material and buy the same thing somewhere else
Now the killer line: "It's £... for you", quoting at least double the price you would pay in a shop. 
AIBU to think they are taking the piss? This is not an isolated incident btw, and whist I would be relatively happy to refund them for their cost even if I didn't want the bloody thing in the first place I am hugely resenting paying a fortune. In theory, I could refuse, in RL, it's difficult when you want to keep a civil relationship with the individual for various reasons.