I do small production jobs. 20, 30, 50 cards. So I don't see the minimum generally.
Send them your info, get a quote.
Yes, they are doing the assembly for me that we either can't do because the parts are too finely pitched, or there's too many to do in a timely manner cost effectively. Robotic pick & place & automated reflow beats laying out 3 cards at a time for days on end after work.