They have one at Shedd Aquarium. Should not be sold to hobbiests. The chances of a hobbiest that can house tarpon(or other large fish, such as Arapaima Gigas) walking into a lfs that has them in stock is pretty slim. I would rather have a few hobbiests, who own 10,000 gal + tanks, have a hard time finding big fish than have tons of fish dying with unprepared keepers.
LFS near me had about 6 shovelnose sturgeon for under $30 each. Not a giant sturgeon, but I still doubt they are going to end up with people who have big enough aquariums to house them.