All the used AX15s I have seen still cost between $600 and $900. I have been searching for a year. It is just not worth the money to buy that and then turn around to spend about another grand on a rebuild. Unless you are doing the rebuild yourself? Idk.
Novak still makes them brand new with brand new parts. It has been reccommended twice on the TJ sister forum. I believe it is $1,600 before tax/shipping.
@machoheadgames may be able to give you more info on that.
I am currently saving up for a Novak for my conversion. I had to buy alot of other needed parts for the switch first.