As much as I see your points and do agree that it is a binding contract, I still have a problem with the "too late" issue. I have over estimated shipping on many occassions and refunded the difference to the person (especially international) just because it's the right thing to do. I dont disagree that he was under no obligation to combine shipping but then he should have simply stated that he didn't offer it. But if you offer it, it shouldn't matter if it was before someone bid or after, it should just be if it was still possible to ship the items together. If he offered it, he should have refunded the difference once they were shipped together. If he didn't, then he should have said so.