I've never done what you did, but props to you because you're doing something very entrepreneurial and I love it.
I don't think you should sell your idea before you build it. Tell your boss about your ambitions to do a startup, and how you saw an opportunity that you believe is very promising, which is the reason you are quitting.
Tell your boss that you always looked up to him, and ask if you two can stay in touch and ask him for some advices for later. If he replies affirmatively, stay in touch, and exchange Emails from time to time, and then when your product is available, ask him to dinner and pitch it to him.
If he replies no, then he's probably not too pleased with your leaving, thus it wouldn't be a good idea to pitch anything. Save it for later.
I don't think you should sell your idea before you build it. Tell your boss about your ambitions to do a startup, and how you saw an opportunity that you believe is very promising, which is the reason you are quitting.
Tell your boss that you always looked up to him, and ask if you two can stay in touch and ask him for some advices for later. If he replies affirmatively, stay in touch, and exchange Emails from time to time, and then when your product is available, ask him to dinner and pitch it to him.
If he replies no, then he's probably not too pleased with your leaving, thus it wouldn't be a good idea to pitch anything. Save it for later.
Best of luck man!