What is year and est value browning 2000 sn13203-c67 12 gauge?

B2000s made prior to and including some of 1976 used the last 2 digits reversed for year. So your C67 was made in 1976.

These have such a wide range of value based on condition, scopes, et.. Value is too difficult to be accurate without seeing the gun. Condition which includes the amount of original finish and original configuration will determine value. Recommend taking it to a gun shop for appraisal.