Last time I went to the doctor a few years ago without health insurance and paid out of pocket it was $200.00 just for the initial doctors visit and then the checkup costed me another $200.00 so in total I was billed and paid $400.00 for the doctors visit without health insurance.
There are also free clinics available to those who don't have health insurance or cannot afford to pay for doctors visits but you have to fill out forms and get qualified and meet the income level to be approved for the free clinic.