I'm getting into electronics quite a bit. My main attraction is power supplies at the moment. I've been putting together a collection of switching and linear supplies ranging in all sorts of topologies.

I'd like to buy an O-Scope off ebay or maybe one of these new DSO o-scopes on SeeedStudio.

However, I don't know what frequency range and/or how much bandwidth the scopes need to measure. (Weird wording, sorry). Is 30Mhz sufficient? Or do I need more? Like 100Mhz? More?