https://www.youtube.com/watch?v=8ts5J09Y7Gc found this video about a super cheap oscilloscope thing and thought some people here might be interested in it (ping @starkatt and @Kyresti, who i know are into this sort of thing and may not have a scope yet)
it's a really bad scope, but it's also really cheap, and it's somewhat usable up to a few MHz (particularly if you use third-party software that people in the comments talk about)
-F
there's also a followup video where they use it to diagnose and fix a faulty C64, and this one shows off the aforementioned third-party software https://www.youtube.com/watch?v=PyFeBAcg7ls
-F