I've been in the same place you are now.  I've had huge parcels sent for surprisingly low postage, some even free postage.I've just gone ahead and paid and there have been no hassles, item just arrives. There could be any one of a number of explanations.  I would just go ahead and pay and see what happens.  The seller is responsible for the listing. (it says so on listings) so it is up to them to get it right.  If they don't, they really can't (shouldn't) ask for more money.  This is a bad selling practice in my opionion and in that case, I would tell them to cancel the sale.  I take into consideration the total cost when purchasing, and won't pay more. Also, if someone is stupid enough to get the postage wrong, do you really want to deal with them? This being said, I did make one exception for a new seller, who had miscalculated postage and sent them the extra, but only because they were new to it all.  Otherwise, I make no exceptions for seasoned sellers.  I had one try it on and I think it was a deliberate attempt to get more money because I was the only bidder. She wouldn't cancel, so ended up sending it for the quoted amount. At the end of the day, you have to be the one to decide how to handle this.