Cheap mechanical pencils can be refilled with colored lead

Carla ordered a 24-pack of these cheap Bic mechanical pencils. I tried one and I like it a lot. The lead diameter is 0.9 mm and it has a number 2 lead inside. It also contains one extra lead in the barrel. A 24-pack sells for about $0.25 a pencil. They are supposed to be disposable, but why not buy a bunch of 9mm lead for cheap and keep using the pencil? You can even get colored leads!