This is truly bizarre. I'm looking at the exact same car and had some of the exact questions.
After researching repair costs I'm thinking an extended is absolutely necessary. High pressure fuel pump failures, wastegate failures, iDrive rebuilds requiring dealer service, no way I want to pay for those on my own.
I have two options with an extended. I'm a member of the Virginia Credit Union. They offer a 5 yr/100k warranty in the 3k range on this car. The same warranty is $1k for an 08 STI. This warranty is through Mercury Insurance. It has a good rep online.
My other option is a Carmax car I'm checking out. Carmax offers a 6 yr/125k warranty for $2600. I'm leaning in that direction. $100 deductible where they take off $50 if you bring it in to Carmax to be serviced. It's an exclusionary policy meaning that they list what is NOT covered as opposed to a list of items that are. They also offer rental coverage during repairs. I find this attractive as I have no idea if BMW will give me a loaner for a car I didn't overpay them for in the first place.
I dig the car. The auto trans is stunning it's so good. I'm typically a manual diehard but this transmission has my head turned.