Sorry Gasman,
One of the only dive shops that books trips to the rigs is The Scuba Company in New Orleans, LA. One boat leaves out of Venice and the other out of Port Fouchon. And, no the trips are not cheap, but a way better price than the Flower Gardens ($395 or something for a two day trip). Rig Trips vary by which boat you wish to use. If you use the one out of Venice it is $150.00; the one out of Port Fouchon is $120, both boats include diving from 6 a to 3-5 p, bait , ice for the fish, and tackle to fish during you surface interval, and an ice chest full of ice for soft drinks and lunch (you provide). It does not include gear (i.e. tanks, weights, weight belt, etc.) The Captain out of Venice promises blue water dives and will go to the point to guarantee that you will spear many fish (unless you are a newbie or do not wish to spear fish). It is, by far, a superior trip to the one in Fouchon.
It's is all in the experience you want to have on a dive trip, but I guarantee - it's like nothing else (including Florida).