Your rifle is likely a Marlin Model 336. The versions made for the various stores (Sears, Western Auto, Montgomery Wards, etc) usually had a plainer finish, stocks made of hardwood instead of walnut, etc. Excellent rifles, just a plainer version. Depending on condition, anywhere from $150-$225. Really good deer rifle, in my opinion.
Which Model?
Mossberg
Proofhouse.com has a chart that might help
50-125 or so
50-150
go to e-gun part
100-300
Proofhouse.com has a store brand chart.
100-450 or so
100 USD
50-200
Western Auto Supply Co. Made in USA