Dennis,
Good buy as that pan is probably worth double to triple what you paid for it. Not too rare but you don't see them often. Made late 20's to early 30's, Best Made, along with Puritan, Challange, and Merit, were Sears tradenames. Griswold made marked cookware under the Best Made, Puritan, and Merit names well into the 30's. Sears had their "Good, Better, Best" grades of items. Best Made was the top of the line while Puritan was lessor quality. Later they shifted around the tradenames some but they still probably had the good, better, best grades. Favorite and, later, Wagner made iron cookware for Sears with at least some being of the lessor grades. Another version of your skillet (same p/n) does not have the S. R. & Co. marking on it but just says BEST MADE, No.3, and the pattern number. I don't know if that is earlier or later than your pan.
Steve