Those guns are actually a lot more expensive then I would have guessed for 1965. Adjusted for inflation, prices have really come down over the decades.Before 1968 you could order any non-class-3 gun you wanted and it came right to your door in the mail. Hell you could pay in postage stamps if you wanted to.
Guns are a lot harder to get now.....Even one you might buy at a flea market where still legal a post-'68 gun will likely have some kind of 4473 paper trail.
This ad was from 1965 and Interarmco was just across the river from DC here in Virginia.....It was also a CIA front for insurgent weapons to be sent to countries the .gov was trying to overthrow.