Physical for me. I just can't read for long durations on a screen. I just can't. I need the tactile feeling of turning pages and having a physical thing to hold and take with me. In that same vein, I have a hard time even reading softcover. One of the biggest reasons I read anyway is to get away from screens/technology anyway. I also like having a physical library in my bedroom that I can look at. I understand that these are all really objectionable, prissy reasons to prefer physical.

For your second question. I've had good luck with eBay, at least as a US buyer. It helps that USPS ships books really cheap for sellers and most stores that I see usually have more than 1 item on my wishlist so I can knock out a bunch of books in one order, get them used (better for the environment), and avoid Amazon