Transmission solenoids?

My 2000 LS200 stalls intermittenly and sometimes doesnt start. The codes were 1779 and 1780. A garage told me it translates to faulty transmission solenoids. He won't look at it since these trannys are very complicated. Is this hard to do? Price? I called the dealer they apparently need to look at it and can't tell me the price until i spend 90 bucks for their diagnostics. Anyone know anything about this issue? TIA