Anyone know how much the AFF software option costs?

Cost is usually assosiated with getting somthing in return.

In this case, Aff is only for point to point type program code. If this is what you're going to output it does work ok, if you're willing to settle for feeds below 100 inches per minute. It is the only way to get decent feed rate compensation through geometric changes in radius and angle on a Fadal control. You cannot get real time feedrate compensation without it, on a Fadal. Just remember that it does NOT work for any code that uses G2 or G3 circular interpolation...

http://cnczone.com/forums/showthread.php?postid=17955#post17955
see post #4

and see post #12
http://cnczone.com/forums/showthread.php?postid=26220#post26220