They want your expertise. That alone, should be worth the 1/3 equity they are offering you. There should also be some type of ongoing compensation for your time spent. You mentioned that they have access to funding. Isn't any of this funding earmarked for developing the new product?
If they are willing to compensate you for your actual time spent, this would have some indication as to how serious they really are.
My initial gut reaction, after reading your question and statement, was your potential partners might be looking for somewhat of a free ride, without having to actually put any real skin in the game. Your "skin the game" is your knowledge.
And bottom line, you don’t sound overly impressed with their proposed product concept. That in itself, would make me leery of involvement (on a pro bono basis) even with the offered equity.