2014 Toyota Corolla, 75k miles. Bought at 52k miles.

Every now and then my car makes some sort of noise when driving. The noises have changed through out the years but sometimes go away for some time before coming back. I've gone to two auto shops and they've taken it for a drive, both ultimately saying nothing is immediately wrong with the car since when they drove it the car made no noise.

I showed someone else a video of the sound being made, but they said a diagnostic of the car to see what the issue was is about $150. Is this price unreasonable? I assumed car check ups were always free. But it annoys me that previous dealers said nothing was wrong with the car when clearly something is.