Keep an eye out on the big box houses. I bought a dual-trace 20 Meg scope for under $400. Off brand? You bet! But, plenty of bandwidth for audio work, and it's been going for 5 years now.
I would also like to try one of the computer based set-ups for their ability to store measurements, but I don't know enough about them to choose an accurate one. I am not sure I trust the average computer audio card to be the front end of a piece of test gear, so that kind of let's out the software-only choices.