I don't care about the £12 (17€) as long as it keeps the developers motivated to work on new content for S3.
Honestly it's really not that much money and how many people have purchased iRacing content for more than 400$ and barely touched the Sim although they've spent a lot.
I bought S3 on the 20th and had much fun on Rockingham so far. I can say it's definitely worth the money.