In the unironic way. I expected it to exist in some form, but being this formalized? wow.
Anyway it's apparently still a thing https://inspirationalwomenseries.com/mail-order-bride-sites/ 
And you used to be able to get them from Ukraine! https://www.imdb.com/title/tt3249478/
I saw an ad from the like 1930s for buying "healthy" indigenous children from those residential schools to do farm/house work and "raise" until adulthood.
settler colonial states and their affection for slave labor are inseparable.
not just slavery, not just child labor