Try an oscilloscope for under $200
Inexpensive pocket oscilloscopes are appearing out of the woodwork lately. While most are merely novelties, there are a few that may actually be handy general-purpose instruments that you might consider keeping in your toolbox. I'll briefly review several current offerings--mostly designed and manufactured in China, but readily available on eBay. In each case, I provide a link to the eBay store, as well as brief specs and features. I don't necessarily recommend any of these, except as conversation starters. But, many of the high-bandwidth oscilloscopes look useful. Interestingly, higher price does not equate to higher performance. Very high (relatively speaking!) bandwidth oscilloscopes are available for around $100.
Several of these are also available from alternate sources. I don't specifically recommend, nor have I dealt with, any of these vendors. As with anything purchased via eBay, it's buyer beware, and take the usual precautions. I might point out one scope that will be available as a KickStarter project. The oscilloscopes are sorted from lowest to highest price.