It's manipulation even if the outcome is considered good. Did it change your behavior, or intend to change your behavior? Yes? Then it's manipulation.

The truth is that you did not come up with the idea to buy it. Their goal isn't even to convince you to buy it. Its to convince you that you yourself want to buy it, and if you do, you decided it all on your own.

Think of it this way. Could you have gotten a better power tool somewhere else? Surely. So why that one? And, since money was spent, wouldn't it be in your favor to just believe you made the best choice?