This is a great place for this topic! Thanks for posting! It sounds though that you need advice about pricing rather than what constitutes a dozen of cookies. Pricing is a function of cookie size, of course, but the greater driver of price is complexity of design (as decorating time can be quite long for more complex designs). Our site has a number of great blog posts about cookie pricing. I've posted two below to help get you started:
http://cookieconnection.juliau...icing-for-cookiers-1
http://cookieconnection.juliau....com/blog/from-dough
Best of luck!