I have 2 hobbico CS-65 servos that were toasted when connected wrong. I have been told this will require new diodes in the servos. What would this repair cost if sent to hobby services? I know it will cost 15$ for the first servo and 5$ for the second. So what about the parts costs? Do I have any other options? Thanks in advance for the help.

I doubt if the diodes were hurt because there are none. Most probably the custom IC was burned out, probably cheaper to just replace them and save the old parts for gear and/or arm replacement.