A Sears 51L built on the HVA action was most likely made in the early 1960s, probably still under contract with High Standard. (Earlier Sears rifles were on FN Mauser actions with High Standard barrels and stocks, later they got guns from Winchester.)
In 1963 a 51L was $120 when a Remington 700ADL was $115, and your choice of a Remington 700 BDL, a Winchester Model 70 or a Swedish Husqvarna HVA for $140; and presumably of comparable quality. The 51L is not a real common gun, I have seen more of the 50s and 51s on Mauser actions.
I do not know the current dollar value, I doubt they have kept up with other guns of the same original price range. But the full stock would help. I have never seen a Sears with full stock, although they were fairly common on Husquvarnas.
