$10,000-$16,000 depending on you're exact needs (i.e., if you need just a car for commuting to work, $10K, a minivan - $15K, a truck $16K).

Beyond that, I feel like the additional cost is a "discretionary" expense. In other words, after I have paid my tithing, retirement savings, regular savings, mortgage, and all of my bills, the rest of my budget is basically discretionary. If I don't spend the money on a car, I could spend it on vacations, eating out, or other entertainment.

So basically, that's the decision - how much value do you assign to driving a nicer car vs. the other things you could do with the money? Different for everyone, I suppose.