The SV4401A low cost VNA ($350 USD)

[joeqsmith]

https://usa.banggood.com/SV4401A-50KHz-4400MHz-Vector-Network-Analyzer-7-inch-Touch-Screen-100db-Dynamic-NanoVNA-Vector-Network-Analyzer-p-1953814.html?cur_warehouse=CN

Claim 100dB dynamic range below 1.3GHz.  1001 data points at 400 data points per second and 25 averages.   Very slow as we would expect.   
50kHz low end is nothing new.     
They claim the 6700mA/hr is a feature.  I don't see where they talk about the run time.
It looks like it may have a built in step attenuator for the output level w/ 1dB resolution. 
They don't mention the serial interface protocol and that would be a deal breaker for me. 

If you get one, post some data off it.

[Grandchuck]

I wonder if it would support the design of crystal filters?

[joeqsmith]

Yes, measuring crystals and crystal filters would be a good one.   I doubt it would work with that anti-gain, tuned amplifier I put together to demonstrate a case where the squarewave drives can cause a problem.  If they cap the bottom end at 50kHz and it's closed source,  the original may still out perform it on the lower end.  Does the firmware crash after 10  minutes of use?   

[LM21]

Clone of NanoVna2?