I used to buy all used copies of books. Why spend the money on the new ones when I was just going to wear them out? I don’t remember the name of the site now, but I was part of this club at one point where I could trade back and forth with other members and get new “old” books all the time, just for the cost of shipping.
And then I discovered SERIES. Beautiful. Matching. SERIES.
You can’t just go buy used copies of them, because you’ll almost never find a matching set. It is possible, but difficult. Especially in the right condition. And it is so much lovelier to find them in a boxed set, if they come that way! Of course, that means I can’t buy it until after I’ve already borrowed the entire thing from the library…or wait until I buy it to read it. Catch-22!
Still, buying whole series and seeing their gorgeousness is definitely a guilty pleasure of mine. These are just a few of them, I have many more!