is it a fuel pump?!

i have a 00 sunfire which somtimes likes to start for a few days then not start for a few weeks. this mechanic who works for dealer ship says he almost 100% sure its the fuel pump and i need to replace it. do u think this is it because im going to buy a new fuel pump next week and i dont want it to not be it and waste my money. are fuel pump replaceing common in sunfires?

this has been happening for months now bought a new battery, spark plugs and wires, fuel injector fluid still nothing has helped it!

Rent a fuel pressure guage and check the fuel pressure at the regulator. If the pump is bad you will not get enough fuel pressure while the engine is running, especially if it drops significantly when you rev the engine. If there is no pressure drop then check for something else. You may also want to purchase a new FPR and replace it first to see if anything changes. It is a lot cheaper than a new fuel pump.