The problem with midas or any all around shop like them will get you the absolute cheapest shocks/struts and charge you the most they can..more than likely sell you some monroes or kyb gr-2's...both are okayish for oem replacement, but they only run about $70 per piece, so $280 tops for all 4. Roughly 1 hour of labor per front, then .5 hour for the rears, then attach a $80 alignment, sounds like they want your $$$. You could save a little dough and put the rears on yourself with very little mechanical experience, its just 2 bolts behind the wheel and no spring compressor required. You can also rent out a spring compressor from autozone for like $30 and its free if you return it. The only thing I would do is have them align the car and do the work at your residence.
2009 Cobalt LS XFE U74
Mods: K&N Typhoon Intake, Option Cat-Back Exhaust, Cosmo Short shifter, Maxxim Ahead 17X7's, MPx shorty antenna, FE5 Strut/shocks, Tein S Techs, Moog endlinks, Moog spring seaters, ZZP shorty header, LSJ downpipe, LNF front grille