Immobilizer Failing, or ECU, or Ignition switch?
 

2002 TL Type S 140k miles on it.

My car quite often won't start (immobilizer light flashing). I take the key out and put it back in several times and eventually the light goes solid green and I can go.

It totally died on Friday...stuck the key in, I see the immobilizer green light for an eighth of a second and then nothing...no flashing, it just totally went out.

I took it to my mechanic...for $116 he told me it's probably the immobilizer. I had a remote start in it and they unplugged that from the immobilizer wires and it started up right away but then it still acted questionable as it has been (so maybe it could be a bad wiring harness?)

So my question is this: should I just take it to the dealer and have them look at it *shudder*

Or should I try to find an immobilzer/ecu/key/ignition switch kit on eBay? ($80-$140)

If I go for the immobilzer/ecu/key/ignition switch combo does my ECU part number have to match the one I buy?

My ECU is part# 37820-PXG-A52 and I have only seen the lone ECUs on eBay, not the immobilizer with key/ignition switch and ECU.

If I just buy an immobilizer will the dealer program it for me? Does it have to be in the car to program (because if it's in the car, the car isn't running)? Same with the ECU.

Thanks!