The manga series K-On! has been out of print, at least in English, for multiple years. This includes the Shuffle, Highschool, and College editions. The only version stil in print is the Omnibus, all of the original 4 boks in one. This can be a problem for mutliple reasons stated below.

1. The Omnibus, being all 4 books in one, is expensive, which can be a problem for fans that don't have that kind of money.

2. Some fans may not want to dedicate themselves to a series right away, preferring to get the next book once they've finished the last one.

3. Reseller prices of the individual books can be even higher than the Omnibus. Believe me, I saw a used version of volume 4 being sold for 65 US dollars.

4. The Omnibus doesn't include the Shuffle, Highschool, or College versions, rendering them nearly impossible to aquire.