Horn - I think coryj was pretty close. Depending on condition. You can pick one up at the local gun shop that is clean except some minor 'huntin' dings on the stock for anywhere from $225 - $275.
With the caplock, the bore condition and the area around the nipple (snail) is where the problems usually occur.
I would take the prices on some of the sites like gunsamerica with a grain of salt. You can get some decent prices there but most of them are way high for used guns.