It depends on the quality of the housing (I assume the LBS is supplying both wire and housing). Avid Flack Jackets go for $30 brake, and $30 gear sets, at JensonUSA, or $60 for just the parts.
http://www.jensonusa.com/store/produ...ke+Cables.aspx.
If the LBS is iselling Avid Flack Jackets for $80 total, then it might seem to be a reasonable price for an LBS.
The $16 labor doesn't seem terribly bad to prep, install and adjust the brakes and deraillure.
Also, this is probably something you can do yourself.