"They way I see it, if it costs $500 in raw product (no matter what the protein), that's every thing included...food, plates, foil, cutlery, all incidentals including gas and taxes, charging $1500 for the event is what's paying for my time."
Pretty arbritrary number, and to just make a sweeping statement that this is "all incidentals" doesn't really give an accurate picture. All sorts of things to consider: did you buy from Sam's or Rest Depot, if you did you're paying for a membership, equipment depreciation, travel costs (very few people, especially in the Northeast will have consistent business selling in their backyard every week or have events right around the corner), gas money spent driving to purchase product, insurance, water for washing, propane or whatever you use to heat water to wash; and again no one has even talked about Sales Tax - and the accountant you'll hire to do those taxes, and your LLC formation, routine trailer or truck maintenance, etc.
You're leaving too much out.
"you may have to cut into that profit of that specific meat a little to satisfy clientel for the sake of keeping a positive light on you just by making it available. Kind of the "you have to spend money to make money" saying goes. It may be a smaller profit margin looking at it in black and white, but it may be benificial in the big picture by bringing in more customers."
Already your formula starts to break down then if you're giving larger portions to please customers; but you're right - try charging somebody $6 for a 3-4 oz. portion of sliced brisket and see what kind of reaction you get, not that impressive on a plate.
So if you're giving larger portions to make it look good and bring in more people now you have to buy more raw product to feed those people and the initial numbers you cite are shot.