I saw some shelves done on a show one time.
They built a shelf that was essentially a box with the back side missing. They did it with 1X s. It is a little hard to explain but it went like this.
Build your shelf out of 1X6 the length you want, box it down so that you have an inside that is 1-1/2 opening. That's a top, bottom, left side, right side, front side. You will end up with about a 3" thick shelf.
Mount a ripped down 2X4 to the wall with screws hitting studs so it is sturdy, you can then mount the "box" to the 2X4 by sliding it over the 2X4 and then placing screws though the "box" into the 2X4 there by creating a shelf that has no brackets.
I hope I explained it well enough for you, it's difficult w/out pictures.
But I think it is an easy, cleaver looking set up.