Wheels straight up don't cost that much if you don't create a new wheel mold, it is not unlikely those cheapo wheels were made in the same factory as 75$ freeride wheels for the same production cost. The difference is the 75$ one 100% slides well and you as a customer 100% knows that. The other ones, its iffy, but not imposible.
In terms of factory's for brands that have come about in the past 7 or more years, you are likly not going to have made a wheel in america. We double checked that as we wanted to make some in the US, and had our multiple emails ignored. The factorys in the US are said to be at their max but don't want to expand.
Elsewhere, their is a up and coming Japan factory I hear, but most brands go to China. I'd estimate a rough 70%. With that in mind there are 5 thanes that are easily accesable to have the duro altered and poured into a premade mold, or if you drop a few K, into your own mold. There are pretty much 5 basic thanes from China, if it feels "like" another wheel thane, it very likley is.