i think they are party sized - at least, the wedding chart says 16, 12 and 8 is 180 servings. very few businesses use party servings - but i they do, the per serving price is higher as they get more cake.
dalinchis - beore worrying about the particular cake, you need to sit down and igure out your basic costs lots o posta on how to do this, and it does take a bit of time. wiltons chart tells you how much batter to use aswell http://www.wilton.com/cakes/making-cakes/baking-wedding-cake-2-inch-pans.cfm
and to work out the servings, just play with the numbers til you have pans that you think will stack in a good way (8,10,12 is a good start) (you might also want to start your own post, as it will probably get more answers)
mom2my3girlz - 14,12, 10 = 172 and im too tired to try and do more math to get closer - but not go any lower.