Prochem charging 300% more than something is worth? Now I've heard everything ;-)
Can you tell me specs on the pressure regulator? Make model?
This is the paper I got with it, it’s the part number 31800.055 if I was you I would call carbs unlimited and order the whole thing from them, that kit is about the same price through them as it was on the ebay link you sent, and they carry that pressure regulator and they can help you with tuning questions and whatnot also