Looks like Tayda no longer offers USPS shipping.
Used to be that in addition to UPS and DHL, US customers could select USPS. Then apparently what would happen is they would package up the order in Thailand, then bulk ship a bunch of such orders to a facility* in Colorado, where they’d be re-sent to the individual customers via USPS. Which was a lot slower, but a lot cheaper for a small order — maybe $3 or so for just a few small parts. Definitely the way to go if you weren’t in a hurry.
No more, apparently.
* Return address seemed to be a residential neighborhood, so “facility” may mean some guy’s dining room table.