Recently the motor on my fan went out. In the climate where I live, an AC is not optional. So I called around to have it fixed. The first company I called said that I needed a new motor. They said in order for it to make sense to put that in, they'd have to install an entirely new system: new furnace, new AC, and possibly new ducts, too. He explained this by saying that due to the age of the units (17 years), he couldn't guarantee how long it'd last. It could be 5 minutes, or 5 years. This would cost $4000. They would not do it for less.
So I got a second and third opinion. Both the second and third opinion agreed with each other, which was that the AC just simply needed a new motor, and that with a new one, there was no real reason to expect it to go out for a long time. And as for the furnace, there was not one thing wrong with it, so there was no need to fix it.
The new AC motor cost us $158.62 (with tax and labor). Compared to the $4000. that it would have cost us had we not gotten a second and third opinion, that's a savings of $3841.38!