i have been going to a new sushi place lately....and they give you a ass load of prime cuts for a really good price....i think most of thee stuff is stolen/illegally imported 
bench
Best thing is that you get grade A tuna only in Japan. They buy all the best tuna from all over the world.
Tuna fishing is a fucked up job, i have seen a program on Japanese TV about a tuna fisher last week. It's a tough job, many hours on the sea, and if you are lucky you catch one fish per day. The fisher doesn't get those high amounts for the fish, they have to catch much more than 3 fish a day. If that eas enough, every Japanese would be a tuna fisher.
If you can, try to get Chu Toro or Oo Toro. This is the highest grade of fatty tuna, best taste.