I wish I remembered these things better. I grew up in what was a rural section of my city with no stop lights, two stop signs, and a lot of farm land. The only places that sold them were 7-11, the closest of which was about a mile away, and Tinee Giant, with the closest being about 5 miles away.
I bought series 1 from the Tinee Giant only because they didn't have baseball cards. They were the ones left in my pants pocket and destroyed in the washer. Series 2 also came from Tinee Giant, but series 3-5 and 7-10 came from 7-11. I distinctly remember trying to figure out what the products were on series 3 from the checklist.
I remember having to trade for a Windhex that was stuck on someone's notebook at school to finish series 4, but I never knew about Bum Chex or Choke Wagon. I do remember trading series 5-10 at school, and talking about whether or not 7-11 had them and how the next series was already out. I remember talking my dad into taking me to 7-11 quite a few times to check.
I vaguely remember my sister, who was much older and married, helping me to buy and finish series 6 in one day. I think it was from a Tinee Giant that was farther away, but I don't remember one being where she lived.
I don't really remember series 11, but I bought series 12 at the concession stand where I played baseball.
After that, they disappeared, and I only found out about the later series, die cuts, wacky ads, and reissues when I was in college, so maybe it was 1983 or 1984. My parents bought me the missing sets for Christmas that year, when they were really affordable. I don't remember the prices, but the ads came with a Good 'n Empty, for maybe $40. I don't think any of the others, including the die cuts were more than $15-35 each, and the reissues and 1982 set might have been $5 each. We didn't have a lot of money, and they probably spent $150 total, which was really generous.