Car won't start. Help!

Over the past week or two, I noticed that when I'd crank the car, it would almost struggle (at times) to start. Just the other day the car has ceased to start at all. The only two sounds you hear when turning the key is the whir of the fuel pump priming and one click (I assume it's from the starter motor).

Here's what I've already eliminated:

- Not an immobilizer key issue
- Not a battery, battery cable, clamps or fuse issue
- Not a starter motor, solenoid or relay issue
- Not a fuse issue (I checked them all)
- Not a fuel pump issue

I've tried everything short of sending it to the dealership.

Any help would be most appreciated.