Update - I just bought a cheap digital 20MHz scope. Never had a digital one and I'm totally sold on the audio applications. I honestly didn't realise all the neat advantages over my old Tektronix CRT scope.
This is what I bought and the price here in the UK was below £200. I calibrated the probes with the 1K 5V test signal and then tried out the various features and the best bit is the measurement menu - you can measure RMS, peak to peak, frequency and loads of other parameters and display these under the trace on the screen. I squirted some audio into it from the computer here and my MacBook puts out just over 600mV p-p on a 1KHz test tone. I really can't see me using a conventional digital multimeter when this is so easy compared to my old scope. Even adjusting the timebase is easier - press a button and it grabs the waveform and locks.
I also note my MacBook has a small DC component on the audio - connecting the cable just raises the trace about .2V before the audio is brought up. I've not even scratched the more advanced menus yet. In value for money terms I'm very pleased