It sometimes depend on where you live and whether it is even offered in the state. My former home state in New England does not allow colonics, or did not 2 years ago when I was living there.
I now live in MN and just did an online search for "colon hydrotherepist" as well as "colonics in MN" and came up with only one online. It charged $74 for first visit and $64 there after. A sister of mine will be going to another that charges $60, the therepist that I went to trained her but said it is an open session, which I prefer not to do.
If you have not done so already, I recommend that you read up on colonics, and remember, it only flushes out the colon...not the small intestines.
Good luck in your search, it is well worth it to your health...