Yes, he sells a lot of Guild knobs. Used to sell fixed price. Now mostly uses auction listings for the knobs, and I've seen him get as much as $78 for a set of four.
It's interesting, BTW, that GPR and bassplayer's shipping addresses are located in the same Ohio county just SE of Columbus. I don't know the story, but it seems almost intuitive that there would be some past connection there.
As you posted, when Parts is Parts has Guild knobs in stock, they have the best price. Plus, free shipping if you spend $50. Actually, they just sent me a bunch of them to fill an old back order. So, I'm psyched.
Anyone who shares my degree of paranoia probably should view Guild knobs as a "get-'em-while-they're-hot" item. It would be no surprise to learn they are no longer being made by Fender because Guild know longer makes electric guitars.