Not sure but I will check. I shipped 26lbs to SFBay for $10. Shipped 8lbs (17x17x7) box to AZ yesterday for $10. Both UPS. My card gets held at the retail price then it changes to the discounted amount. So according to the current hold, the AZ box is a 63% discount. My initial guesstimate was $60 for the seats, so that is probably pretty close.
See my shipping FAQ brainstorming thread for ideas about using your employer shipping options. If I ship through the hospital that I consult for, I can do a set of wheels from Seattle to FL for $25. Figure 70-80lbs across two boxes. That was with Fedex, but think of the amount of boxes that hospitals are receiving (using their account). I’d use them but they are a pain to deal with.