Climbing Chalk Bags
Chalk bags are not safety items or for protection, so you can buy what ever takes your fancy. One word of warning would be to make sure your hand fits in it easily, there's no point in carrying chalk if you can't get to it!
Also, have pockets, some zipped or velcro'd. It gives a handy place to store some precious keys or sweety money and are worth a thought.
Think about how you're going to attach it to you whilst you're climbing too, as a small snapgate maybe better on a climbing harness, but a chalk bag belt will be better whilst bouldering.