Mombo,

We use the actual USPS postal rates. We usually ship Priority Mail with Insurance unless a seller requests that we go with a cheaper rate (which is usually nominally less expensive) or without insurance. We make it clear that if they don't want insurance, we can't guaranty against damage or loss and we have actually had buyers do that. It scared us. But we are happy to say they arrived in fine condition - Whew!

There are a few sellers that actually make a bit of a profit from the shipping/handling/insurance charges, but this fortunately is not happening as much as it had a few months back.

The source we use for figuring our shipping and insurance charges is http://postcalc.usps.gov/

Hope that helps.