In my experience mikchez is right when he says that a crack addict won't quit until he 1)wants to quit 2) Links pain/negative consequences to his crack use. Those consequences can be jail, loss of loved ones, loss of self respect (which if it hasn't already occurred then he probably isn't ready to quit), a near death experience, death. Once he has fulfilled these two requirements, he will will probably want to quit by any means necessary, crowded rehab or not. There are many expensive rehab centers across the United States that are not too large, or crowded, but will keep him at least 90 days and urge him to transition to a sober living facility afterward for a period of time. These facilities, if you have the money, can be very effective. I do not know the name of the facilities that deal specifically w/ crack addiction, but you can find them by going to the following website and finding the link within the page that says something like.."I need help with addiction or Have loved one with addiction problem"..don't worry they won't put him on a TV show..it is just a resource.. A&E Intervention (it is the TV shows web site)..or A&E The Recovery Project (it is a project related to the show). I know how hard it is to overcome that addiction, but believe me it CAN be done..he just has to want it for himself. Don't give up on him unless it is going to destroy your life as well. Remember he has to face the consequences of his actions, what ever those may be.
A good place to start might be face to face. Nobody can make an addict quit he has to want it or your wasting your money, and your in for more heart ache. Al-anon is a program for people that are involved with addicts and alcoholics look it up in your area.
Jails always a good place to start recovery program. I'm a recovering crack addict there will be a time when the drugs quit working thats when he is going to want to quit.
Not until he links more pain than pleasure to his using will he want to quit.
Good Luck
Peace&Love