I know that people used mail system and sent out actual letter before spam and scam took over. But something as far back as 1928, I didn't thought it would be cost friendly/feasible to send out mass mails/flyers to Model-T customers.

Bangshift.com's reader sent one in to them. The letter is from 1928;

Prices in the brochure are surely correct according to that time but it was amusing to read because I had my parents tell me quite often when growing up and asking for some money for you know..;'In our day all months ration was bought for a quarter or half of a dollar...', and today, the whole dollars gets us nothing!

ps: Talked in my local currency terms, but I am sure things aren't much different elsewhere.