Legal or not, markets are markets and prices will be affected similarly. Prices going up in one market won't cause it to go down in the same "black market". Its all about supply and demand; the more legal it becomes the more "steady " (or openly known about) the supply is; demand was just high as balls that day, it being the first.
But as twostrokenut stated-- the flood will drive down costs. Actually, production drives down costs and I'm sure they were ready for that day and had crazy supply, them charging that much was just taking advantage of the flood. But prices will definitely start to drop lower than ever before.
Move to Virginia, a pound of top grade still goes for 6 grand