St. Jude's (do a google search for St. Jude's substance abuse treatment) has a scholarship program. You have to write a letter, you will have to call them to get the information on the scholarship (it's not available on their website). They have long-term treatment though (3 months) sometimes the Catholic Archdiocese has rehab programs that are free/low cost/sliding scale, so I would call the closest one to your town. I went to one in st. louis (strictly for women) for 21 days. I always detoxed in the psych ward at a local hospital as well (so I could be comfortably medicated with anti-nausea, anti-diarrheal, and sleep medication to withdraw more smoothly. It also helps that you can't just walk out of a psych ward, you can walk out of rehab. Sometimes, those 1st few days, you can talk yourself into NEEDING to get high just 1 last time- which is never 1 last time.
Also, think about looking into a sober living facility for when he gets out of rehab. A lot of them are free and help with job placement *they usually charge a small "sobriety deposit" when you are placed* they only charge you rent once you get a job. It's a great place to transition back into the "normal world" and the frequent drug testing along with not being in a place you used to get high in, helps keep the cravings at bay.
If he goes to a substance abuse treatment center, they usually help with continued care (outpatient, transitional housing, etc) and hopefully he gets the most out of it!
Good luck!! I know how hard it was for my mom when I was actively addicted.
You're in my thoughts and prayers!