Note that this is an enhancement to an existing therapy. Depending on where you are in the world and the healthcare providers you have access to, the existing therapy called Transcranial Magnetic Stimulation (TMS) may be an option.
Unfortunately for SAINT it looks like you also need fMRI to correctly target the therapy...that's going to be a bit tougher to DIY.
You can also search this TMS FB group https://www.facebook.com/groups/285541688306686 for "saint" and find other people's experiences.
Edit: Apparently, the clinics that claim to be offering it might just be doing something that is loosely based on what is publicly known about the SAINT protocol. Dr. Nolan Williams hasn't released full details, so it's not possible for clinics to replicate it exactly. This clinic https://www.cambridgebiotherapies.com/accelerated-tms/ talks about how they've tried to reverse engineer the protocol at the bottom.