Nowadays, it goes both ways. I know someone who took 30stacks, they'll pay you to marry them, You might meet this women in college or some situation that allows them to be in the country temporarily but they are looking for a way to get permanency; usually Asian countries.
As for you buying, obviously it isn't as straight forward as the name implies. But you find them on websites, my favorite is
www.latineuro.com which keeps some BAD ones in the Brail and D.R section but they don't keep good records, I think it's illegal to market themselves as such a site either so those sites will just sell you profiles of women looking to hookup, you pay for their contact info and photos, maybe a translation service on a chat, and you set it up yourself passed that. Then you go to their country, get married there, scoop them and bring them back. Women in these 3rd world countries are loyal though, old fashion, they ain't leaving you or taking you for your money until like Eddie said, they become too Americanized.
Also being around the military, isn't uncommon at all. Dudes love to go to Korea and come back with a wife who speaks very little Engrish but does all the wifely things without complaint and just stays home, even more prevalent than the "brothers who get stationed in Germany and scoop them one," trend.
There was also some locals and some playboys who just used the site to hookup with local women. I might try to find that thread.