Are you sure my dog needs new batteries?

Had to take the car to the shop today. The problem I have is that mechanics and veterinarians are both the same beast to me. They can pretty much say anything they want, quote any price I want, and I have no idea if they're pulling my leg or not. The key phrases from the mechanic today were:

Blown Intake Manifold
Cracked Sway Bar

I have no idea what these things are. I can't turn around and pointedly ask if the manifold is actually blown or is it just winded. Maybe my car doesn't want to sway so why worry about a cracked bar? How do you determine a fair price when your knowledge of cars is "They go vroom vroom". It would be like my vet saying my dog needed new batteries. My only response could be "Is that double A's?". *sigh* I just hate it when you can actually hear the cash register sound in their mind when you say stupid shit like that.