Bargain on price.

Not in a "regular" retail store, but in any case where a single person has the authority to adjust the price: any kind of street market, for instance.

True story: I was in England and with some friends who live there, and we were going to an "artist open studios" day. I mentioned that back in the States, I routinely offered less money to the artist than they were asking. Not a whole lot less, just 10-20%. The "asking price" for a piece of one-off art is completely arbitrary anyway and the artist is almost always happy to bargain.

My British friend looked horrified. I don't know if everyone there would consider it rude, or just her.