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.
For those taking this seriously: fMRI requires careful presentation of stimuli and a complex analysis. It’s not just a scan. I doubt you can get that at Scans’R’Us.
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.