The door latch assembly will run about $400. The switch alone is about $130, according to the price list on this site, if they don't tell you they have to replace the whole assembly. I'm guessing the switch shown in the parts diagram is the one in question. I didn't check the labor, but I would guess maybe another $100, or so. I can only hope it is a bad wire or connector. Interestingly, my door switch on the passenger side ('91) is not working, either, and I am going to look at it when I go in to check the condition of the power window mechanicals. I can usually fix switches, if the problem is only corrosion. Good luck on your problem.
Regards,
Bill