Unless we have an agreement otherwise I keep source files like AEP, Photoshop, etc. The client owns and pays for shoot tapes and final masters. The way I look at it is that the final product is the house and the aep file is the blueprints, seperate copyright and seperate product. If a client want to get the source file at the end then I would put some sort of fee in there and it would be in the original contract stating such.