Cheap osciloscope
At the end of the thread, there’s a link to a whole bunch of hobby oscilloscopes!
http://forum.sparkfun.com/viewtopic.php?t=18548
This PC based scope looks promising:
New to the Lab: QuantAsylum QA100 Oscilloscope & XMOS USB Audio
Talk of other bench oscilloscopes
http://www.diyaudio.com/forums/equipment-tools/181052-400-oscilloscope-fft-spectrum-analysis.html