You won't have to pay to send him to rehab, the first hurdle is him saying I have a problem and want to change. Then by all means look up places local that deal with addiction, if he's willing take him, they will take it from there. They often also have services for family too, so you get help in what you've dealt with, a whole multitude of things.
They will find a rehab unit often far from home, this is to make sure family can't enable the patient, as when you see a person suffering your instinct is to help.
The first hurdle is him wanting change. You can't force it on him unfortunately.
I dealt with a sibling with an addiction, supported them through it all, supported them through relapses. They really have to want to stop, or they won't offer treatment.
My sibling wasn't on drugs, but I've helped a few people and seen people on drugs, I've seen people who have tried rehab.
If you look into Russell Brand he is a person who does a lot for addiction charities. He was quoted on c4 news as saying addiction is anaesthetic for the soul, so alcohol or drugs, there's an underlying issue that needs sorting, thus rehab & post rehab services.
I don't even know what crack does, but volunteering I came across people doing all sorts who told me their stories, it all made sense as to why mentally they were suffering, thus self medicating.
Any support I can give you please don't hesitate to ask.