I think you will like 1,2,3 Magic.
My ds7 does try to manipulate me with the "if I do this, then can I have that" or he'll do something nice and then ask for a reward. I thank him and talk with him about how we aren't rewarded with things all the time but by the good feelings we get from helping. We are still working on this.
Consistency is crucial. It's the hardest thing when you are at it 24/7. Also, positive reinforcement has much longer lasting effects. Punishers (loss of marble, time-out, etc) are very effective in the short term so anything you can do for positive reinforcement is better especially when you consistently ignore the undesirable behavior.
