I wish the fuel here in the UK was that sort of price! Granted the lowest RON available here is 95 but even that at the moment is between £1.23 and £1.40 (A LITRE) NOT gallon!, it costs me as much as £70 GBP ($96 US) to fill up , as for using a lower than recommended RON, I would think it was not a great idea!
We pennie pinching Canadians are right behind you! You're lucky that your lowest octane is 95 nothing to worry about.
I do use 91 but TSI can run on 87 octane, the majority of American and Canadians use the cheapest gas, its human nature to want to pay the least, they don't know any better. When you fill up, just glance over and see what other VW owners put in their cars. VW knows this and takes this into account when they tuned the ECU to support 87 and 91 or greater octane.
If you're TUNED you pay the Piper.
I can see both sides, last month when I'm home on Hilton Head, I pay $2.60/gallon, as soon as I get back to Toronto the price jumps to $4.90/gallon (Price based on 3.785 litre US Gallon).
When gas prices start rising again, remember what was said.