Joes in Miami gets thier stone crabs from here:

http://www.keysfisheries.com/

which is down in the Keys in Marathon.

I was there on October 14th and split a pound of jumbo stone crabs with my wife. Along with 3 bottled beers and some fries; it was a nice light dinner that was in the $40 range for the 2 of us. I'm a seafood lover and these stone crabs were simply amazing: sweeter than any lobster I've ever had. The "sauce" they serve with the crabs - supposedly just mayo and mustard - sounds terrible until you try it; it must have a few spices added in because I sure cant re-create it !

This is a ramshackle place with picnic tables; all the tables are on the water. We had a few beers and watched some stone crab boats come in, met some of the boat owners, and watched an amazing sunset.

I've been to the Joes in Chicago, and believe me, this place is 10X better !!