Make sure you go to every orthodontist in your town. I went to three different orthodontists for my DD (13). The first one wanted $5,000, the second wanted $5,300, and the third wanted $3,500. They all had the EXACT same treatment plan, all three graduated from the same school of dentistry, and all three had very high recommendations. I went with the cheap guy. His office is what I would call "low budget." He did not have game boys for each child in the waiting room, he did not have a "treatment coordinator" and his office complex is older and in a cheaper rent district. Try to stay away from the slick practices. They might make you *feel* better or more confident but they aren't necessary and they drive up the costs.
As far as kids really needing braces: actually in most cases kids do, even if the teeth don't look that crooked. Rather than look at your child's appearance, it is more important to look at their bite. If they do not have a perfect bite (where all the teeth line up and interlock properly), they are going to have many problems in their mid to late-adult life. Improper bite causes gradual wearing down of the teeth so that the back teeth are dull, making chewing things like meat very difficult. Misalignment of bite also causes gum pockets to form which will lead to gum disease. None of these problems will be come evident until much later.
As for teeth shifting. I had braces at 13. My orthodontist (and any good orthodontist should tell you these things) told me that if I did not have my wisdom teeth removed that my teeth would shift. So after the braces came off and before my wisdom teeth started to come in, I had them removed. My friend had braces also. She had lots of room in her mouth, so the removal of the wisdom teeth was never required and her teeth are still nice and she is almost 40. My teeth still are very straight too. I have some mild shifting that only I can see. My orthodontist DID want me to wear my retainer for life. That will prevent shifting, but most people will not comply. Also, even if you don't get braces, your till will shift as you age.