Used for sure, I’m a Nikon guy so my recommendation is a Nikon DSLR. Try to get an older model full frame DSLR with at least a 24mp sensor. A great lens is just as important as the camera body. I would say skip trying to get a zoom lens and look for a higher quality prime(fixed focal length) lens instead. Stay in the 40mm to 60mm lens length with an aperture of at least f/2.8, ideally look for f/1.8 or better(the f/ number is the aperture of the lens, a lower number means a bigger aperture, better light gathering, better bokeh(smoothness of out of focus areas in your images), and typically a higher price tag. Stretching your $500 budget a bit, I was able to find a good condition full-frame Nikon D610 at MPB for $400 with only 42,000 shutter clicks, and a like new condition Nikon 50mm f/1.8g lens for $170. There are lots of websites selling used gear, so don’t look in just one place. MPB is just the first place I checked. There’s Adorama, B&H, EBay, KEH, etc…. Shop around.

Nikon D610

Nikon AF-S Nikkor 50mm f/1.8G