As far as I can tell the Analog Discovery you mention is quoted by Digilent at $279 and for this price you get two 100MS/s analog inputs, so that means that you

As far as I can tell the Analog Discovery you mention is quoted by Digilent at $279 and for this price you get two 100MS/s analog inputs, so that means that you can't sample anything above 50MHz max (and in practice you probably won't be able to do a lot of useful work above ~40Mhz). With modern circuits routinely having signals in the hundreds of MHz that's fairly limiting for me. This comment dismisses a lot of measurement use cases out of hand, at least as far as a hobbyist or rudimentary manufacturing test case is concerned. An input bandwidth of 50MHz is still more than sufficient to evaluate all kinds of useful circuits - a few I can think of offhand: * Buck regulator loop compensation and transient response * Large signal audio debug (not suitable for small signal just due to the limits in the analog frontend and the number of bits in the scope ADC) * Basic digital protocol debug If you're tuning a PLL, or need to evaluate DDR signal integrity, or trying to design an audio system with -120dB of THD+N, then yeah, an Analog Discovery is probably not the right tool. Then again, if you need to do any of those work items, then you probably already know that.