It's important to note that the IEP focuses only on the areas that are affected by the child's disability, so if, for example, a child is academically competent, academic goals may not be included in his IEP.
The question of what to include in an IEP for a child with autism is wide open, and depends not only upon a child's needs, but also on the parents' personal philosophy. For example, the question of whether an autistic child should be included in a typical classroom or in a specialized program or school is as much a question of philosophy as a question of what is "best" for the child. Similarly, while some schools and families want their child to receive behavioral intervention, others feel that developmental intervention is a better idea.
While, in theory, the content of an IEP is NOT dependent upon a district's resources, the fact is that a school can make it extremely difficult for parents to insist upon certain expensive accomodations (such as a 1:1 aide). Parents do have the option of taking a district to mediation, due process, and even court over the contents and implementation of an IEP - but that is often a difficult and expensive road to take.