Sounds like a great idea as long as who can wait out the early stages before becoming profitable.
As mentioned MMA is the fastest growing sport lead by the UFC. Unfortunatley in this baseball country, you cannot even find a sportsbar in the Capital who even shows the UFC.
Again another area where this country needs to get caught up. I also believe there could be some talented prospects in the DR, if trained properly. Its just a matter of time before the sport evolves in the DR as well.
If your husband has Brazilian Jui jitsu, thats a great start, but i would seriously consider bringing in the muay thai kickboxing, boxing and wrestling coaches as well and be a full scale Mixed Martial Arts school.
These are the ones that make good money back in my hometown in Canada.