Toyota Repair: Speed Sensor/Speedometer Malfunction, rav 4, sensor replacement

Question
I have a 1996 RAV-4 with manual transmission, cruise control
and 92 K miles.  The speedometer/odometer stopped working
and then the check engine light went on.  The repair shop said I
needed a speed sensor ($ 400.00 P & L) based on the code
reader and once this was replaced it still did not work so now
they tell me I need a new speedometer that costs about
$ 500.00.  Does this sound reasonable to you?  Also, in the
course of replacing the speed sensor could the tech. have done
something incorrectly that would have shorted out the
speedometer?  Does the battery need to be disconnected prior to
sensor replacement to avoid a surge to the speedometer?        
THANK YOU FOR ANY HELP!

Answer
Since the speed sensor was not the problem I would ask to have the old one reinstalled and your money refunded and then repair the real problem which is the speed sensor in the speedometer which means replacing the entire speedometer, this was an obvious misdiagnosis on the repair shop's part and they should take care of it.