How much does it cost to check a bike?

I'm curious, how much does it typically cost to have a bike checked out or serviced? I understand that prices can vary depending on the type of bike, the services being performed, and the location, but I'm just looking for a general idea. Is it a flat fee, or does it depend on the specific issues that need to be addressed? And are there any common issues that tend to drive up the cost of a bike check?