I've packed and shipped big items myself (things like wheels and tires rather than seats). You can get the shipping materials (boxes, protective materials like bubble wrap and/or popcorn) at an office supply store (Staples, Office Max, etc) or at a shipping place (UPS Store). Wrap it and pack it yourself, with enough soft stuff to protect the surfaces that need protecting. Then you can ship it yourself, either through the usual places (FedEx, UPS, the post office) or places that specialize in shipping larger items (Greyhound - yes, it goes in the bus - is often a good choice, otherwise a freight place). You don't need to have a corporate account to do so, and the savings they give to corporate customers aren't all that great anyway. What really costs you is when you go to a place like the UPS Store and you pay them to do all the wrapping/packing (when you can do it yourself) and then you pay them higher shipping rates than you would if you paid on their website and simply dropped it off there.
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