AFAIK US has a visa scheme where you can invest something like $1M and get an investor visa. Pretty common to see immigrants that come to the US and buy up some gas station or other fairly turn-key business to take advantage of this. You don't have to buy a company and then have the company sponsor you if you do it that way AFAIK.

If you have a few hundo' thou' you can get an investor visa that leads toward residency about anywhere, and only a few places like America are more than that.