Here's how it all turned out. I ordered the sensors online, passenger side rear and driver side front. Cost was about $90 each. I got them overnighted to me for $20. Still a huge savings over the dealer.

I installed them myself. The passenger side wasn't bad at all--took about 15 minutes. The hardest part was undoing the clip that held the wires together.

The driver side front wasn't quite as easy. I could get a wrench on the sensor, but again, had trouble getting to the clips that hold the wire fittings. I wound up taking off the inner fender liner, and getting to the sensor from the wheel well. So it took me about 45 minutes to do that one. It would have been less if I'd just taken the fender liner out right away. It isn't hard to do at all, and it goes back together without a problem. All in all, though, it was way more awkward than it needed to be, just because of the wiring clips.

The old sensors had a gray oil residue on them which is why they went bad, probably--not a good sign. The thing has 96k on it. So I took it down to the Toyota dealer and took a bath trading it in on a new Highlander. I've had enough!