Upcycle used bricks for heavy bookends similar to concrete. You can even paint them any color you wish.
Spray-painted rocks are easy to make, and they don’t even have to be the perfect shape to fit on your bookshelves.
Letters of the alphabet, mounted onto small wooden planks, make perfect bookends. Make yours with your initials, your spouse’s initials or just random letters.
Many glass vases already weigh enough to hold up books so all you have to do is fill them with decorations. Fill lighter vases with rocks or glass beads to add some weight.