Assuming theroshyeshiva is correct that you can get scholarships to subsidize everything but $500/month, there is a solution. You could ask him to earn the money himself. If he is homeschooling now, he probably has some time on his hands. If there are pet sitting opportunities within walking distance, he might be able to make $1000/month on 2-3 pet sitting jobs per day. He could sleep in people’s houses to take care of their pets (if they trust him) for around $50/night. There’s other types of jobs, but for a 14 year old who is O.K. with long walks outside in all types of weather, this is probably the best.
You might want to point out to him that he is probably going to need a tutor (at least in the beginning) because there won’t be many boys who want a chavrusa who has “difficulty reading.” What’s more, it’s inevitable that one of the immature teenagers who are his classmates are going to tease him about this. Will he be able to handle that?