I'm not a lawyer but am jumping in anyway...
First is that the laws are likely state specific, but have a look at what your state says about "cottage food sales" to see if they have a list of approved stuff. Probably won't apply though as that tends to be aimed at stuff like jams, spice mixes, cookies, breads, etc.
If I were in your shoes I'd try to avoid any money changing hands. Have the friends buy and drop off most of the ingredients you'll need. If they bring some extra for you to use for yourself as their way of saying thank you for donating your time, even better.
Sadly in this day and age I also have to suggest you make sure your insurance is in good shape. Today's friend can be tomorrow's plaintiff.
Edit: Ha, I see Maple Sticks' insurance post after writing mine. Truly sad that we have to consider that angle today.