I hope it's just my wording that is throwing you off.

Say, for instance, you need a car. For me, if a car costs more than $10k, I really have to think about how reliable it is, what features it has, and generally if I am getting value for my money. This is all because anything over $10k is going to take longer for me to recoup. This is what I'm defining as my impulse buying threshold.

Not really that weird at all. Cars maintain a healthy resale market so if you buy a car with a couple of owners and a lot of miles for $8,000 and drive it for a few months, you can often sell it for the same, or just a little less, than you paid for it. It's not an $8,000 gamble, it's more like a $500 gamble.

Your impulse threshold is about 3x my ceiling price for a car.