You should be able to do them yourself easy enough, prep a sample with your logo, name and all the information you want to see on it for the client to fill in. Then go to anywhere that designs or prints. It’s quite expensive so I just designed and printed my own.
You could always try Etsy as they have a lot on there but people that do design are not likely to know everything that you know about your treatments so something you can personalise would be better than generic with your logo.