We did cupcakes for our wedding back in May. We looked at Oak Mill Bakery in Niles, Jarosch in Elk Grove Village, Bennison's in Evanston and Molly's in Lincoln Park. You can read about our experience
here (page 3, about halfway down). Several people theorized that a regular bakery would be cheaper than a cupcake-specific bakery, but that wasn't necessarily true for us. Molly's is the only cupcake bakery I've been to (and who we used for our wedding), but I've seen the prices at the other places and they're not even close. Bennison's was the only regular bakery we went to that was cheaper, but it wasn't by very much, and while good, the cupcakes weren't close to being as good as Molly's.