Well, Tasca didn't know what I was talking about. Domenic wasn't there. Anyway, I decided to give another dealer a try that I've always had good luck with in the past. I haven't gone there since we moved, but I thought what the heck.... I called them, told them I needed a WIF sensor for an '06 350, and he knew exactly what it was. He said he had 2, and he could sell me one for $18 and some change. So with tax, still under $20. The first dealer was $138.17 before tax!
The dealer that tried to rip me off - Alexander Ford in Murfreesboro, TN (I recommend to anyone not to go there; this isn't the first rip off attempt).
The dealer that treated me right - Mid-Tenn Ford Trucks in Nashville, TN (Always highly recommended, but more so now).