I've also used Aeroprice PC software to purchase my Arrow. It was
very useful. It tended to understate price, I found - i.e. if I
offered their suggested price, I usually lost the deal but that's OK
since people often pay too much for their planes.

The other thing that was handy about it is that you can create your
"ideal" aircraft, then add and subtract items to see how much adding
that 3 blade prop really adds to the value. It's a little
discouraging to learn that you can usually get back only about half of
what you put in.