It may not be so complicated, but it definitely would be a time consuming process, if you want to find someone who is really worth your money. It always depends on your budget and what you're looking to get out of the mentor.
It's good to consider your goal if you're thinking of getting a mentor because it will be like an investment in the first place. You'll also have to take into account how much you're willing to pay to gain more knowledge or experience.
I agree that it depends on a photographer's budget and what they are looking for in a mentor. It is also a process that requires diligence, patience, and accountability. I would look for a friendly and thorough person.