I have bought a car since being here. It's cheaper than buying in Canada and when I move back, I'm just taking my car with me as personal property. Of course, I made sure to get a car that wont need many adjustments to satisfy Canadian standards.
As for property, I'm actually thinking of buying a condo/house. I'd just rent it out when I leave or then again, sell it.
It's true that there is a lot of uncertainty on a TN, but its nature of the beast. I get the feeling of weariness and I can see why you'd want to go home, but for me, and for the time being, it works. Everyone's different when it comes to life management. Maybe I lack in that department
I'm wondering why you insist on going to the border. Why dont you file for a 3-year extention in the mail? It's less time consuming than to drive all the way up and it's my guess, you'd be less at the mercy of someone else's mood. If time is of the essence, I do believe there's a premium service that costs aroung 1K (someone correct me if I'm wrong)
If you like your life as it is in the US, try your best to get it set for another 3 years and use those years to think your next move through.