your shotgun was made by high standard just prior to 1980. value will depend on condition mostly. i can estimate that one in good condition will cost around $200.00 to 300.00.
High Stadnard stopped making the model 66 for sears when the Ted Williams 30 made by Winchester was introduced inteh early 1960's High Standard was completely out of the shotgun busines by early 1977.
THis link is to a chart that shows the dates when these shotguns were cataloged by Sears.
http://www.histandard.info/PDF/Sears%20Shotguns.pdf
J.C. Higgins Model 20
1952-54. Value up to $125. http://www.histandard.info/PDF/Sears%20Rifles.pdf
1945-1959. Value up to $75.
The Winchester Model 12 was never sold under the JC Higgins name.
made by Marlin for Sears 1959 to 1962
70years old priceless
made in 1958 and valued between 150.00 and 200.00
Blue Book of Gun Values
made in 1935.
Which model?
Without a model number and the condition of the gun, impossible to answer.
about 1950