Yes, I use USPS where possible.
I had a recent case I was going to buy a $40US book, but didn't because they wanted ~$17US to ship. It wasn't an Amazon distributor.
For things like Mouser, I often wait until I reach the free shipping quota of $200US or more. Hence no quick repairs in my hobby.
Sadly, not all allow USPS shipping for foreign purchases and use UPS, or the like. A recent purchase for a $130 USB HD TV device still cost me $21 shipping, all in US funds of course. "Local" Wal-Mart, BestBuy and the like don't stock the model I wanted, hence the online order.