J.M.
While no doubt what you're saying is true in some places, I would strongly caution you about blanket statements about schools not wanting to "spend the money." In all likelihood, the school doesn't "have the money" so it's not that they're being selfish, it's that they're trying to best balance the needs of "some" kids against the needs of "many" kids. It's a very very complicated balance.
Also, learning disabilities are not black-and-white. If a child needs a feeding tube or they're going to starve to death, it's pretty clear that the money needs to be spent or the child will die. However, determining whether a mid-range autistic child needs a full-time aide is different. Some "experts" will say that the kid needs the aide, other experts will say that she doesn't. And if $15,000 is riding on it, the school has to figure out the best way to spend that money. I don't know any responsible caring educator who would willingly deny a student who truly needs that aide - then everyone loses. But I know lots of responsible caring educators who would say "lets try without the full time aide and see how it goes." It's not that they're denying services, it's that they're trying to determine how many services the student actually _needs_ not just "would benefit from."
As a parent, it's your job to advocate for your kid, but that doesn't have to mean fight every step of the way. I encourage you to take everything with a grain of salt, but know that just because the school doesn't do everything you would like them to do doesn't mean that they're "denying needed services;" they're doing their best to balance the needs of all students. Good luck.
edit: I sent my response the same time that Brenda (below) did, so I didn't read her answer. My aide example was in no way aimed at her personal experience - I don't know what her son needs. I left the example in, however, because I think it's true.