Special Child, Special Needs

Here is my story. I am a mother of three wonderful, beautiful, and amazing children. The middle child, Tryce, age 8, has high functioning autism. As any parent of an autistic child knows, they do have different needs than children without autism. For that matter, each one of my children has different needs than the others. Unfortunately, my autistic child needs just a little extra help than my others.
Here is where my ultimate frustration lies: all three children attend the same elementary school, ranging from grades 1st-6th. While not my top pick, is where the invisible lines designate my child's attendance. Tryce is not succeeding here, like I know he can, while my other two are doing wonderfully. Here are my options...move across those district lines and uproot my kids from their school so Tryce can attend a school better fit for him, or stay there and watch while Tryce falls through the cracks. We cannot afford the $30,000 a year for the special needs private school so we are left making this decision.
What kind of education program do we have in this state that will not allow me to choose another school for my child? Does the state government really think they know what is best for my baby? All I ask is for parents be given some choices when it comes to their child's education.