You can get a decent used scope for way less than $50. Ebay has them cheap but the shipping will get you to that amount. As they say, it takes one to know one. A 10-20 mhz analog scope is usefull for most applications. Untill you try to use one, you won't quite understand how usefull being able to capture a non repetitive waveform like the digital ones can. If you were buying new (probably down to $300 by now), I would consider one of the DVMs that have the digital scope built in. Like everything else, you learn by doing.