Pretty sure for domestic shipments for say a case of shirts they are quite a bit more expensive. I had a customer ship me 4 cases of shirts from 3 hrs away and they paid like $220!!! Now, I imagine they insured them and did whatever the post office sold them on, but that kind of blew my mind. I remember checking maybe a dozen times(last time maybe a year ago) and I seem to remember it not being worth it. Plus the carriers bitch if they bring you cases.
Are you shipping coast to coast? We use a regional carrier that hits like 7 states, waaaaaaaaaaaaaaaay cheaper than UPS and FedEx AND there is no residential surcharge. I know there are a handful of regional carriers out there, some partner with others to cover a larger foot print also.