You can do good work with even the most basic Oscilloscope.
I had need of one,& bought a 10MHz single channel thing from Jaycar.
It worked for ages,apart from the knobs breaking,& having to replace the BNC connector,until the HT supply for the tube failed.Even that was easy to fix,so it's still useable.
It doesn't get used now as I have a Tektronix 7613.
The two channel 20MHz ones from both DSE & Jaycar are much more capable instruments,if you can pick one up cheap.
If you happen to see an early BWD,be very cautious.
They are quite good Oscilloscopes,& have the advantage of a large,bright display,but a lot of them have a triggering problem.It is fixable,but they are mongrels to work on.
VK6ZGO