I think you guys may also have bought a BT keyboard for your iPad. I think it is quite inconvenient to carry these two items individually. Therefore, I would like to share a link with you guys about a kind of useful iPad bags to carry iPad and keyboard at the same time.
This website displays some tailor-made iPad bags to carry keyboard additionally. It makes them work together as a professional notebook which also have the powerful functon of iPad. I personally think this kind of case is quite cheap and could also meet the need of many users