Try some of those if you don't want to buy weights, or you could make use of things you have around your house like water bottles or cans of soup for dumbbells. (healthyhelperblog.com)
(I usually place a cutting board on top of tofu and a couple of cans of soup / beans). (simplehealthykitchen.com)
At least it is something I am happy to use, unlike the random can of soup that I have been avoiding. (alidaskitchen.com)