I think it is an interesting idea and will most definitely garner attention due to the fact that people will be able to make a few bucks on their own recipes...but I see one major flaw.
What if I go to Kit Lab's site, see a recipe I like and would like to try out, and go to my LHBS to purchase the ingredients? Obviously the person that posted the recipe isn't getting paid by my LHBS.
On the same note, what if instead of going to my LHBS I purchase the ingredients from Northern Brewer, More Beer, etc. because their shipping is cheaper than $15? Again, the recipe creator is not getting what they expect.
Not that I think any of us are really out there just to make a buck (I surely don't think I am retiring based off of my recipes) but I think this is an aspect that will hinder this effort.
Just my $0.02 though...