I don't know where you ship, but I haven't seen $29 shipping in 10 years. Amazing that there's such a discrepancy. That PRS in the big case is HEAVY and I'm sure would cost me close $100 to ship and insure. Been shipping gear for years and have never found prices as low as your getting. I've gone through Staples UPS ship center, Kinkos FedEx, and Mailboxes Etc. I don't bother with the post office because of their limited hours. Its frustrating because if I could ship for $30 I would.
EDIT: I just checked the UPS estimator and it said $50 to Albuquerque. That's still higher than what you're paying and I know it will be much higher going through a contracted ship center like staples. honestly I don't know where I could ship direct, seems everywhere I look to ship, its a business owned by a third party.