When I was really young, Frantz Garage Hardware's Great American Game (1923) was the ticket.
Frantz - APBA.jpg
I also moved through Ethan Allen's All Star baseball that Fred and others mentioned.
Kashin Allen.jpg
But I was introduced to APBA in 1953 (their third year) and amassed a significant collection over a lifetime, some of which I still have. Selling sets from the 50s recently has worked out quite well. Clearly the best "junk" my mother didn't throw away. Even in this condition the 1956 set was very profitable
56 AL New York 1.jpg 56 AL Cleveland 1.jpg
56 NL Brooklyn 1.jpg 56 NL Milwaukee 1.jpg