Patent Idea - How much should I split profit with partner?

If it is guidance you are seeking why don't you involve a consulting company and get your money's worth and then pay your friend for just the storage? There are companies like Fulcrum Patent Solutions that provide such consulting services and help you monetize your product. See link in sources for more information. I hope this helps.

cant really help answer this without knowing what your idea is.. so you should tell us

The marketing of the idea is where all the profits are going to be made. Manufacturing and storing can be outsourced to the lowest bidder...this is grunt work not worthy of a percentage. Guidance does have a price...not sure how much. Seems like he's taking the role of consultant on that one. Could probably buy a "How to Patent Your Product" course somewhere online...I'm sure someone is selling information on how to do that. However, if this guy needs no money up front, then you value. If he's giving you credit on the stipulation that he doesn't get paid unless you make a profit, now you have something. He's actually taking some risk on spending his time and machinery and may not even get paid. In other words, he has some "skin" in the game. Btw, who is purchasing the raw materials to manufacture the product? I'd put as much on him as possible. If that's the case, a 50-50 split may not be out of the question. However, I would make it clear that he is NOT a partner, just your manufacturer and a consultant. I would also take the 50-50 on a sliding scale, i.e., 50-50 on the first $100,000 sold, 35% from $101,000-$250,000, 25% on $251,000 - $500,000, and 10% sales over $500,000. Or whatever you decide. You could sweeten the deal by guaranteeing that he'll be your manufacturer 1 year or 2 years or whatever before you go shopping around for better prices. The thing is, I would make it clear that he is NOT a partner, this is NOT a partnership. He's a hired gun with some resources and you're being generous enough to let him take a slice of the pie that your idea and marketing produced.