You can find modest dresses you just have to look. I just got back from a visit to South Eastern Idaho and saw several stores that had modest dresses. It all goes back to supply and demand. Down here in the Southeast, modesty is not a priority, so I had to look elsewhere. I found some very cute dresses online at http://www.dillards.com/ by Jodi California. I bought this pink one below for my very tall skinny 10 year old daughter. She loves it.
Modest for girls sizes 7-Juniors. They are reasonably priced as well. To me I would rather pay the thirty dollars and not have to search and search. You can click on the dresses and they will take you to their site.