I use a Canon EOS 60D for my primary camera, with a standard 18mm-135mm kit lens. Which was given to me by my dad once he phased it out with a newer camera for his photography business. I'm not sure how much one goes for used, but I'd imagine it might be cheap considering it's 13 years old. But basically, to capture lightning, you want to find a camera that has a good enough light sensor for low-light applications. Kit lenses are fine, you don't really need anything fancy. I'd recommend shooting in manual focus rather than auto focus, and to make things a little easier on you, try and find a DSLR that shoots video as well. Because, you can then go into Premiere Pro or some other video editing software and go frame by frame to take still images. Oh and get a tripod to help stabilize the camera while shooting.
This is one of the lightning shots I took on my Canon EOS 60D. iirc I was shooting at an ISO of 400, an aperture of F8 (might've lowered it to F6.5 at this point in the evening), and a shutter speed of....1/25? maybe 1/50, I can't remember. Now, this picture and some of my other pictures from this same storm were pretty grainy which tells me next time I find myself in this same lighting situation, I need to lower my ISO a smidge. but yeah, I'm sure you can get similar shots like this with similar settings on something like a Canon Rebel T7. Might even be better than this shot honestly, and T7's are pretty cheap as they're a beginner DSLR.