Dale,
I don't know of any place that sells those lips regularly. I have seen people sell them on E-Bay or other places occasionally but they typically sell too high for me.
I make some reproduction Punkinseeds sometimes. As a matter of fact, I just finished 4 tonight. For the lips, I use modified spinnerbait blades, as you suggested in your post. I prefer to use the painted blades. I remove the paint to reveal a heavier weight steel blade, not nickle-plated brass blade as is typical with most spinnerbait blades. I also like the painted blades because they look more like the original Punkinseed blades. I cut out a "V" shape where the hole is and then bend the points back. Drill a hole in each point and and basically you're done.