About 4 years ago I was searching for ways to help my son who was just starting out in a gift high school who had no experience with LD kids. I found a website where a kid with special needs could apply for a free computer. It was meant for college students, so he didn't qualifying. I thought I saved the website, but alas can't find it now that he is gearing up to graduate and head to college. Any know of such a site (s).
Grants like that often are short-term -- so while this one is probably gone, there may be others like it.
Also, check out the disabilities services at the colleges you're looking at. They may not provide an individual computer, but they often have assistive software resources that would be prohibitively expensive for an individual.
A nice grant is paying for my salary helping LD kids at the community college -- and we're installing a 16-computer lab with TextHelp! and other good stuff ...