Weight-bearing exercise is one of the best ways to build (or maintain) muscle mass and bone density. I highly recommend strength training…especially when you get my age! I try to buy weights for less than $1 per pound if I am buying them new, so there are some pretty good deals depending what size weights you need.
Walmart is running some pretty great deals on CAP Dumbbell sets. For example, you can get a set of two 5 lb weights for $8.50. A set of two 10 lb weights (20 lb total) is $17, and a set of two 15 lb weights is $25.50. If you need even heavier, the deals get even better!