$170 seems like an outragous deal! Most likely a $500 bike new if it has disc brakes.
As far as bike repair, go with Aj's if you want no headache quality work. If you want cheap get-ur-done with the possiblility of a long wait time for parts go with Extreme Cycle gear in Riverview.
I have a Shimano XT 31.8 front derailleur just sitting in my tool box and it looks like it might fit your bike according to Specialized web site. What color is your bike and does it have a specific model like "Rockhopper Disc" or "Rockhopper Comp"? My buddy has a Sram X-5 left shifter that is compatible with Shimano front derailleurs. It's brand new and I think he wants $30 for it. I think a new set of X-5 shifters is like $70.
You other option would be to just run it in the center ring (sprocket) since it's not that often that you need the big or little gear. I rode a bike for 6 months that way.
Oh yeah, nothing on a mountain bike is reasonably priced.