To replace, you need to find out the size. Measure from the center of the mounting eyelet on top and bottom. Once you have that, look at eBay and CL for shocks in that size. You can get a decent Fox RP3 with propedal these days.I would guess that in Co they are actually pretty common. Jensen USA has a Fox Float CTD for $320 right now...just depends on how much you want to spend.
Fox Float CTD rear shock NEW!
Fox Float CTD Shock 2014 > Components > Rear Shocks > Shock Bodies | Jenson USA Online Bike Shop
EDIT: I looked up the particular shock you have...I could only find measurements on the 2011 Sensor 4.0...think its the same shock though. It is a 7.5" x 2". Take some measurements and see if they are the same.
2011 Sensor 4.0 vs 2012 Sensor 4.0 - Mountain Bikes Comparison