Check ebay before you go buy a new one, it will be much cheaper, just make sure it works first.
It definitely depends on what you want to do. For example, I would like to get a 100MHZ o-scope because I fiddle around with wireless mics, or bugs, that transmit in the 88-108 MHZ frequency.
Of course there are other options, such as dual trace, or i forget what it is called, but you can store a signal if it is a one time thing, like the IR signal from a remote that does not repeat itself and is too fast too see. There are also high impedance probes that will not affect a circuit when you test it; if you stick a regular probe that is not high impedance in a radio circuit for example, it will throw the frequency off and a lot of other things.
I dont own an o-scope so thats the best i can do for ya :lol: