Originally Posted by
FWAAA
I just booked LAX-MKE for later this week and found that on some aa.com-suggested itineraries, the instant upgrade P was the cheapest available fare at $440 each way plus taxes. Cheaper than the one-way M fare at $480++ or the one-way H fare at $580++ and of course cheaper than the one-way full Y fare at $742++.
I've often seen the instant upgrade fare cheaper than full Y but rarely have I seen it the cheapest available seat on the plane.
It does happen. How often depends on the route and how many days out you are booking. For the sort hops around the midwest I take, I am frequently a good corporate citizen by booking the *UP.