@fozzy40 I agree with @jforbush that you can pay someone to do just about anything but in general you can learn a lot about an area yourself without hiring someone...especially if you already live there.
Remember that with DPC you aren't worried about a large revolving group of people like a store would be. You need 300-800 people in general. You'll have more turnover and a higher utilization for a more specialized practice in general so you will have to factor that in.
But rather than thinking of the patient market, it might be worthwhile to think of the referral market. Who will send patients to you? Will it be primarily PCPs, orthopedic surgeons, massage therapists, local athletic trainers, etc. Make a HUGE list of every potential referral source. Then go visit some and talk with them. Find out what their pain points are. Maybe they want someone who will see their patients/clients quickly or who will provide emotional support or who will send notes back to the PCP or decrease opioid use post op or whatever. Then create your own marketing sheets for different angles (I just use google docs and free clip art for mine and print a 1 page black and white handout that they can easily photocopy) and take them around and say hi.
For example, I do full spectrum family medicine except OB but I prefer young families. I also am located in a pair of office buildings that mostly house small businesses. So I have one marketing sheet titled, "Why Do Families Who See Midwives Come Here?" and the same exact one with the word "Lactation Consultants" switched out for "Midwives". And another that says, "Why Do People Who Work in the Wells Fargo Building See Me?" and another with "Chase Tower" switched out for "Wells Fargo".
In the ones for crunchy young families, I emphasize things like the amount of time I spend, that my office has a playroom, that I'm available by phone evenings and weekends with questions. In the ones for small businesses, I emphasize things like the convenience of going to the doctor over your lunch break, reduced absenteeism from illnesses, and that many people working in these buildings already come to see me.
I could have payed someone the big bucks to think of that but it's pretty much common sense.