Wirelessly posted (BlackBerry: BlackBerry8530/5.0.0.1030 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)
Current BAEC policy is not to make any additional collection when a BAEC member cancels a reward. So if you only paid $5.60 for a domestic redemption on AA, you will only forfeit $5.60 -- even though BAEC's published cancellation fee is higher.
However, if you want to change a BAEC redemption rather than cancel a redemption and book a new one, then BAEC's change fee would apply.
If you're flying on a nonstop to a destination that is not very far from NYC, BAEC will also charge fewer Avios than United would charge miles.