price depends almost totally on condition, and where in the country your located, a decent used one with a reasonably new barrel goes for between $700-$900 last time I looked, but you'll occasionally see screaming deals in yard sales of if you ask around at gun-shows or at local shooting ranges, join a shooting club and ask around, don,t be in a huge rush and Id bet you get a good one for under $600, when some guy gets laided off or divorced
the M1A1 civilian version of the M14 goes for about $1100 used and in my opinion thats a better deal