Are the said parts still on the vehicle or loose?
If it's still on the vehicle, obvious answer is that it takes time to remove from vehicle and reinstall.
If parts are loose, then, you essentially are paying for the knowledge and expertise of the tech performing the task.
Idk for sure as its not very specific as to what you wanted pressed out. It could be simple like a control arm bushing, or something more complicated like wheel bearing (ok not that much more). Most places you go to would use big hydraulic presses rather than the small hand ones you can buy at princess auto. Those I would imagine are around 3-500 ish. Perhaps more.
Again, I could be wrong.
Sent from my LT30a