You know what's surprisingly hard to find? Bookends. Like, basic, flat, metal bookends. I've been looking for some for my bookshelf because it's a cheap plastic contraption from Lowe's and doesn't have sides, but all I can find are really big, bulky, expensive, decorative bookends that take up half the shelf.
I managed to find a wire mesh tray for $3 at Savers, though, so I put my Vocaloids (and Haiyi) in it because they're on the top shelf and most susceptible to tipping over due to being so lightweight, but I still have to put a lotion bottle and a random glass candle holder against one end to keep them upright.
Freaking bookends, man.