When I was looking for help with my younger son, I found very little of anything, including advice, on how to get him the help he needed. I honestly didn't even know what kind of person to look for to ask questions. I tried our pediatrician, but he was useless.
HSLDA has some helpful info, but not enough.
I found a local woman who was pro-homeschool and did testing, so we got him in to see her. We found out his issue was his working memory (I hadn't even heard of that before). I had thought that his issue was auditory processing.
We finally ended up spending hefty sum of money to get him the help he needed through a speech and language pathologist. He spent an intensive 7 weeks doing Fast Forward last spring. God provided the funds when we needed it, and we have zero regrets about putting him through the program.
Now I have a son who is teachable. I didn't have that before. Getting the right kind of help is worth every penny if there's any way you can do it.
I would say a SPL is the best way to go. Personally, we felt that if there was something that would help him, we had to do it. I would have sold a car, a camera (I have some expensive gear) or whatever I had to just to get him help. And taking him to the SPL every.single.day was a HUGE inconvenience, but worth it.