Keeping your art and artistic ideas in a sketchbook is a great idea. Its good to keep a collection of your art in one safe place. Blackbooks are also good to do art trades with your friends so you can exchange pieces and collect their art.
These are nice high-quality sketchbooks that are cheap only in price. They feature super nice drawing paper (224 pages) that is great for many varieties of markers. Also, there are plenty of pages inside so you can keep that art flowing.