1999 Pontiac Firebird Please help me diagnose my car proble

Electrical problem
1999 Pontiac Firebird 6 cyl Two Wheel Drive Manual

I have a 99 firebird v6 3800 series. I have been having problems with it starting. And every now and then it will die on me. I had a mechanic look at it with a fuel pump pressure it read 50 lbs. He had said it wasnt getting enough gas. It doesn't want to start but he told me to click the key ignition a cpl of times to I guess prime it. Then it starts after I do that. I just need a professional to tell me if it is really a fuel pump. If so could I interchange with another pontiac firebird yr? Or could I just buy the pump instead of the whole thing. Theses pumps are very expensive. Please help! With this problem.