I don't really care about owning the manga physically, so I've just been reading Dragon Ball on Viz's website. In the US at least, a monthly membership to their Shonen Jump vault is only $1.99, so I got all of Dragon Ball (and most of Shonen Jump titles that have been released in English) for only two bucks, and I can just cancel on the months I'm not reading anything. It's a ridiculously good value for someone who just wants to read it and doesn't care about having a collection.