The UFC DOES pay for airfare and hotel for the fighter + 1. However, for fighters from Korea, we have to come in at least 10 days early (2 weeks is better) in order to get used to the time difference. The UFC tickets flights (and books the hotel) for 4 or 5 days before the fight. So, the fighters from Korea (and other foreign countries) have to pay the difference in fares and the extra days for room and board.
If you assume that a fighter is going to bring, at least, their coach and a sparring partner (for KTT, they bring me as well), that means the fighter is paying for 2 extra plane tickets (usually between $1200-2000 RT from Seoul). Add in 5 or 6 days of room and board for 4-5 guys and it starts to add up! Then take out US federal and state taxes, then the guys get taxed again in Korea. Subtract paying the fees to the coach and sparring partner... and what's the fighter left with? Unless they get a bonus (or two), or are making a really good base pay, not much.
If you think about the fact that KZ (before the Poirier fight) was making $6,000 as base pay, then you'll realize that for a lot of our fights in the US, we end up losing money. But, the fighters do it hoping to build up to bigger paydays and more sponsor money.
I think the $1,100 that Stun Gun mentioned was probably the difference in fares. The UFC pays for the basic fare, but if you decide to change your travel dates, the fighter is responsible for paying the difference.
A lot of people say it's the same for all foreign fighters, not just Asians, but the main difference is that for South American fighters there is little/no time difference. For European fighters, the time adjustment is easier because there isn't as much of a time difference to begin with AND it's harder to adjust to travelling east, as opposed to west. I don't know why that is, but it's definitely different. We have a hard time when going from Asia to the US, but coming from the US to Asia is not as hard (same for Europe to the US).
Anyway, just my/our experience...