And would you look at that, even MORE source that confirms that as of 2008, Dragon Ball has 350 million sales with an average of 8.33 million per volume from Senkei Shimbun (a mainstream Japanese newspaper).

>「DRAGONBALL EVOLUTION」（ジェームズ・ウォン監督）は、世界で3億5000万部を売り上げた漫画家、鳥山明氏の代表作「ドラゴンボール」の実写版で
>"Dragonball Evolution (directed by James Wong) is the live-action adaptation of Akira Toriyama’s worldwide mega-hit manga Dragon Ball, which has sold 350 million copies globally
https://web.archive.org/web/20081212210945/http://sankei.jp.msn.com/entertainments/entertainers/081210/tnr0812100742001-n1.htm
By 2008, Senkei (a major, legitimate Japanese publication) publicly reported that Dragon Ball had already sold 350 million copies.
>2002
Tokyo Anime Fair / Jump Expo, Dragon Ball has sold 260M.
>2005
Toei internal, industry doc confirms Dragon Ball has sold 300M (160M from Japan and 140M overseas).
>2008
Oricon + Senkei confirms Dragon Ball has sold 350M
>2009
Tokyo Anime Fair reaffirms that Dragon Ball has sold 350M.
>2013
Toei also reaffirms that Dragon Ball has sold 350M copies.
>2025
No official updates in 17 years. Still "260M" on paper which Dragon Ball has passed A LONG time ago.

If you factor in:
>17 more years of reprints (in dozens of languages)
>Digital distribution (global manga apps, Shonen Jump app)
>Kanzenban, Omnibus and Full Color editions
>Anniversary reprints, box sets, and collector’s editions
>Pirate/bootleg editions, which are rampant worldwide
Then Dragon Ball has VERY likely sold around 475 million copies globally, and is close to 500M if it hasn't passed that mark already.