I've ordered a ton of parts over the last 15 years. I stay away from UPS if at all possible. USPS is great because there is no expensive handling and duty fees but has limitations on sizes. A few vendors will not ship USPS though. Some vendors I believe have special deals with USPS/UPS/Fedex and can offer "all in" prices which is nice. I ordered tires from Tirerack and they offered this and even included GST which is great because I knew exactly what my total cost would be. I've never got a bill after the fact except from UPS!