I'm sorry I showed up too late to this party to be any help to Ben. But here's a range of advertised 1912 Cadillac prices:
a hard-topped Coupe - $2255
a limousine - $3200
phaeton (4- or 5-seater) - $1800
roadster (two-seater) - $1800
torpedo (another 4- or 5-seater)- $1900
touring car - $1800
These prices are not low, but it's true that there were plenty of more expensive cars on the market. The now little-known Garford went from $3750 for both the four- and seven-passenger tourers to $6000 for the limousine.
Here are some Peerless prices advertised for 1912:
38-Six Torpedo - $4000
24-Four Town Car (a smaller limousine) - $4200
60-Six Berline Limousine - $7200
48-Six Phaeton - $5000
40-Four Touring Car - $4300
Interestingly, for many companies, passenger capacity did not seem to impact price. The 1912 Corbin 30 Roadster (two-seater) and Corbin 30 Touring Car were both advertised for $2000. The Corbin 40 Torpedo (4-seater) went for $3100 while the Corbin 40 Touring Car (7-seater) went for $3050.
Model T's were not as affordable in 1912 as they would be by the 1920s. I believe they cost between $6- and $700. The Model T Town Car, the limousine version, went for $900.
The cheapest car was probably the Brush Runabout, which went for about $350. These were very basic two-seaters that I think were kept for recreation more than utility. An article of the day reported that the Brush was favored by young debutantes not only in American cities, but in London and Paris as well.
I don't think there really was a car for the middle class in the way that we think of now. Even the Model T would have beyond the reach of the average commuter. Second-class passenger Benjamin Hart owned a car (I don't know what kind), but he was the exception.
