I am always on the website Amazon looking for books to read. Often times, I will compare the cost of an ebook vs the physical copy. Usually, the kindle version is cheaper and that is how I save money buying books. If the book was meant for school or something dense like an encyclopedia, then I opt for the physical copy. Also, waiting until some type of holiday comes around is a good idea to buy ebooks on sale. Sometimes, there are random sales so it still pays to check back every once in a while.
There are some ebooks which are cheap while there are others which cost the same as the physical books. For textbooks I think to save more money you should try finding a used copy of the book because since once you are done using the book you may not need to read it again, you could sell it again and use the money to buy another book.
I agree, ebooks can be incredibly cheap especially for new titles. In fact, there are so many titles within the Amazon store that you can purchase for less than a dollar which is ridiculous. There was this one time wherein I downloaded nearly a dozen ebooks for less than five bucks. Lol.
I think buying ebooks does save you money in the long run because there are sites where you could just pay monthly fees and get access to their library. Sometimes just looking at the second hand book market can maybe just yield you the same result but since ebooks are much easier to access I suppose the time you save should also be considered as well. There are some books that are equal in price both in physical and digital versions but I guess when it comes to that it would mostly just depend on whether you give more importance to saving time and travel money to get to the store or if you consider having the hard copy to be more important.
