Canon EOS R100 with CBG/Custom Battery Grips accessory
For being the least expensive mirrorless interchangeable lens camera, the EOS R100 packs a great punch; it is basically with older M-series camera with a full-size RF mount camera that can still accept the old EF-series EOS SLR lenses via relatively cheap adapters.
The great thing about this particular example was the inclusion of the CBG/Custom Battery Grips accessory, which was 3D printed with ABS in Poland. This saved me from having to order and wait for it, it is a $95 item. If you put couple of 18650 lithium ion cells in it, the camera will run continuously for a day. You will struggle to fill a 128Gb CF card (it didn't come with that, but it's an inexpensive item from Target). Also, I find the "stock" camera to be slightly too small to hold comfortably, in particular there is no place for your right pinky to sit, which can cause some cramping with extended use, this grip fills the gap and makes the cameral easier to hold steady at the expense of making it slightly bigger. Since the grip is printed with ABS plastic, it adds scarcely any weight.
Very happy with this camera and accessory battery grip. Crazy good image quality and incredible focus speed. If you don't need 4k video (it will shoot regular HD very well) or the tilting screen, the EOS R100 is an incredible deal.