The power door lock on the driver's side in my 95 Lumina will not open when I hit the power door button. It locks fine, but will not open.
Is there a way to fix this, or do I need a new lock?
Is this a hard part to replace?
and lastly, is it costly?

it sounds like your window/door lock switch is bad, since you're having problems with both. That switch is dealer only. Those switches are fairly problematic, and the chance you got a bad one from the salvage yard is pretty high.