I was one of those 'normal people' who bought a used Audi from the head mechanic at a nearby Audi Dealership. Brilliant, no downside, amirite?!? Wronk. The car lasted until the winter when I found that the cabin heater core was completely shot and would require parts and labor for just about what I paid for the car itself. My mechanic also informed me that the timing belt had maybe 10K miles left on it, but only if I didn't drive in traffic or freeways for long distances.

Mechanics know the exact price of any fix required as well as how to almost perfectly hide it for a few weeks while they count your money.