Does anyone know how much it cost to install a factory type coast guard approved Genset and A/C in a 2003 42ss? The boat has all the switches but needs the A/C and Gen Set.

It depends on what gen. set and air cond. you chose. Just do it right the first time. You should really allow a certified marine installer to put these things in your boat. You are right the hard part of fishing wires and finding places to put switches have already been done. If anything ever happens, all you have to do is show the recipt to your insurance company. You can shop the internet and get some pretty good prices.