I have a mitsibishi galant07 the valve where you add feron has a leak.

Not sure about Fla. , but in the D.C. Metro area , you can expect to pay from $95.00-$195.00 ,for A/C system evacuate and re-charge with dye(use dye in case there is a leak elsewhere).I've had two in the last year and a half that were seeping from the factory. Seen several others over the years with a valve leaking.More than half had other problems in the system , so be prepared for what you can't see as well as the valve you can see.Good luck.