I checked Ebay.nl Marktplaats.nl and asked on circuitsonline.nl
You asked on CO if you could use a 50 dollar toy-scope kit. But for 50 euro's you can find plenty analog 10 to 20 MHz scopes. Analog scopes are very fast realtime, they are only blind at the retrace. In a nutshell, the analog scope measures a voltage at time x, this signal is converted in a voltage that moves the beam. There is a very very short delay between the moment it is on the CRT and time x. There is a sawtooth voltage that moves the trace from left to right. This is not in steps but continue. At the end of the screen, the sawtooth voltage has to return to zero and that time it does not show data on the screen..
Besides that the scope does not show channel 1 and 2 at the same time. It switches between channels. This is the way most dual or more channel analog scopes work. For even more realtime they made dual beam scopes ( you then have a dual beam, dual channel scope but they are rare) But an analog scope will show the signal only as long as it is really there. So the jump from 0 to 12V from the switch is as long visible as the real time it takes. There is no easy way to capture that. (they used f.i. single shot and scope cameras for that.)
So an analog scope is not good for looking at one time events because it is to fast for your eyes and brain to measure the interval from the screen. A DSO is better for this.
A DSO is very blind most of the time. It measures at certain very short intervals. So it misses data between those steps. How often they do that, is the sample rate given in samples per second. Before visible on the screen it has to compute that data. So they are not really realtime. Some digital scopes measure 1 channel at a time like the dual channel single beam analog scopes, Some measure 2 channels at once like the dual beam. But a DSO only measures a fraction of the time, like less then 10%. Fast = more realtime = more expensive. There are more factors like the rate they refresh the screen, how much memory, delay between channels (but that is in ns so neglect able if your measuring ms or us).
I understand that you want the relative difference between cameras. That is not a problem. But I would try to show the effect in practical use instead producing numbers that look fancy but do not say a lot. I have no clue if the absolute numbers are useful. Your eyes need more time to blink as that camera to register, adapt and record the event. I am probably wrong but it sounds to me as snakeoil. To much unkown factors, different setups and testers that do not really know what they measure. (the influence of al other factors) Sounds like someone did something that looks very technical and the rest follows. Show the real effect during flight. If it causes a real problem it must be easy to demonstrate it in practice (I think, I never flown a drone with camera).
Sounds a bit like comparing cars at topspeed if you only use it in the city. But again, not my field of expertise.
You should compare you test setup with different scopes. If the results are more or less the same the setup could be good. If they differ a lot the setup is not good and you only measure the test gear instead of the camera. Just my two cents