I don't have a catalog with a 1921 retail price list, but this Dec. 1, 1920, Retail Price List shows a GHE at $129.
Dec. 1, 1920, price list.jpg
For Jan. 1, 1912, the GHE was $78.75. Prices started going up fast in 1916, Jan. 24, 1916, the GHE was $84.74. By Nov. 18. 1916, the GHE was up to $91.35. They peaked about the time of your gun, then came down a bit in the on into the 1920s.
By the Jan. 2, 1922, Retail Price List, the GHE was down to $113.75.
Jan, 2,1922, price list.jpg