I have been offering $2.00 shipping for years on lower end cards and free for higher end and have not been dinged at all. Sorry to hear the issues with your buyers. Can you link us your profile so we can take a look?
"He had no teeth, and he was slobbering all over himself. I'm thinking, 'You can have your money back, just get me out of here. Let me go be an accountant." I can't tell you how badly I wanted out of there." -QB John Elway On Jack Lambert(1983)