Yesterday I went to lunch and when I was ready to leave, I get in and the car wont start. Never given me this issue before. I checked the batter terminals, they were tight, didnt see anything that looked disconnected otherwise.
Took a hammer out the trunk- tapped the starter and it started fine. Drove back to work turned it off, on again no issue.

That being said, I want to know how can I confirm officially that the starter is going bad before I buy a part that I don't need?

 

could be the starter. another common problem with random no start is the main relay. This can be fixed for free by re-soldering the connections.

You can usually tell its the MR if the no start happens only when the car is warm (because the solder connections expand).

 

My feelings are the starter based on further information ive been given....

 

If you hear a loud click, it's the contacts inside the solenoid. If you can see 2 large wires/bolts outside of the solenoid (one is the battery to starter wire) and you bridge them, you should see sparks and the starter engage. I just replaced the contacts inside my starter and they were horrible - no continuity. Now it's got more ***** than most B-series starters I've tried.

Otherwise to check the battery you'd put an Ohm meter on the battery and see what the voltage drops to when you turn the key. If it drops below 10v it's probably the battery.

 

Check your grounds and your starter wiring..mine had poor contact and would start or not start at diff times. I've had grounding issues cause all sorts of weird problems. Hope it helps anyone