Just something else to remember... not to be a naysayer, but the minute you start charging, you open up a whole can of worms.
If heaven forbid your smoker starts a fire on your property (say, an errant ember floats into your rain gutter and catches some old leaves....) and you've been charging for your cooking - your insurance company could (and most likely would) deny any home-owners insurance claim. I've seen it happen to a couple of my woodworking buddies who did a little side business here and there. House catches fire, tools not covered/Tools catch fire, HOUSE not covered! Even if its not much, if you charge, then the whole thing becomes a business and not a hobby. And basically, you're not covered.
That goes even more so if someone should get sick from your cooking. Not saying that they ever will, but just in case. if you gave them the food "as a gift to a friend" then if (worst case scenario) they sue you, your insurance should cover it.
If you SOLD them the food... not so much.
I'd think twice about it. Seriously.
Let them buy the food, the charcoal and wood - and buy you a six pack of your favorites as thanks for throwing it on the smoker for them. The minute you start charging for labor or marking up your materials, it is no longer a hobby.