[kenshiromusou]

Yo, friends.
Could you help me with one sentence?
当時かなりのハイベースで音楽集等が発売されていましたね。北斗の拳だけでも
相当に御多忙だったと思うのですが。
I'm not sure that's "very busy with". Summarizing: "OST discs were sold on large scale. Although I think you were very busy just with Hokuto."
I don't understand ハイベース and 相当に御多忙 here. Is my shot close to correct?