The ones I've seen come in a 16 or 20 oz. cup. layer of bbq (have seen both pork, brisket, or a combination of the two, in separate layers, layer of mashed potatoes, another of bbq, topped with mashed potatoes, a cherry tomato, and a squirt of bbq sauce
Charge 5.50-6.00 a pop is what I've seen, let the market be your guide