This could/should be something the school can help you with. I can't remember the specific section of the IEP, but there's a place where they note if the child needs assistive technology. Obviously your son does. School staff should be able to hook you up w/ vendors for reading devices so you could do trials. SD may or may not pay for their use at home, but at least a trial would help you figure out what works and what doesn't. Like Sheila said, if he needs assistive tech to do homework the the SD should provide it for home use.