So how would a 2002 Specialized FSRxc bike be comparable to a 2007?
 

One with a monitou fork and fox float rear, and avid disc's. Would it even be comparable to a 2007 FSRxc? What would be a decent price for an 02 in good condition?

According to the Specialized website, the 2002 FSR XC did not have discs and the front fork was a Rock Shox SID.
As for comparablility, the 2002 was an S-works model with a totally different frame. I believe the 07 model is heavier, and I know it has the newer designed rear suspension.
As for price, about one year ago my neighbor purchased a 2002 or 2003 Stumpjumper FSR, (V-brakes only) for $800 with shipping. I thought he got a good deal. Hope this helps.