After taking my car to the dealer today because my engine & maintenance lights were on this was the diagnosis which they said would run about $500.

Now is this a DIY project or the dealer or mechanic has to do it?

$500 sounds cheap if they're putting a throttle body on it.
I don't think there's anything special about putting a new tb on the car, you'd just have to do an idle relearn.

I don't have my books in front of me, but I'm guessing that the TPS that the accelerator cable goes to is reading one thing, but the tps on the throttle body is not reading what it should be based on the first one's reading. Too bad you don't have freeze frame data on when the problem first occurred.

Before spending a bunch of money:
I'd first get a helper, remove the intake boot to the throttle body. Have the helper turn the key on, engine OFF, have them floor the accelerator to allow the plate to open all the way. Clean out any carbon there using a small plastic brush and some carb cleaner. Put it together, disconnect the battery. Then once the battery is back on, start it and perform and idle relearn.

The VTEC pressure switch is above the oil filter next to the VTEC solenoid.

You might seek some goodwill assistance from honda. 18009991009.