I'm pretty sure that to qualify for a tourist visa it is only necessary to prove that you have MET within the last two years. It could be in HIS country, or HER country or even in a country that isn't home to either (I have heard of western guys who have arranged to meet their FSU sweethearts in Egypt and have successfully used photos from that trip).
In any event his plan to do it on the cheap isn't going to work. Unless she can prove substantial reason that she will be compelled to return home (family obligations, a responsible job, real estate ownership in her name), embassies will gnerally base their decsions on past experience. And most embassies have found that young, single FSU women tend NOT to return as they are supposed to. That's the problem.
When I called the USCIS regarding proof of relationship, they "advised" not etched in stone to have pictures of us together with her language in the background. Reason conoffs have wide lattitude in establishing what constitutes proof of relationship. They also did stipulate that you would have to meet out of the US to get a K1 visa. What was projected to me was don't give the conoffs at the consulates any reason to RFI anything. Including proof of relationship. So bottom line, you better meet in her country or chances are you we be required to provide more proof of relationship and under FAM these guys are provided a wide berth.
So bottom line meeting in the US will not qualify for a K1 visa, so it's better to get on a plane head to another country, preferably hers and document the evidence, ie plane fares, hotels, etc. you know the drill.