Cheap VNAs?

[n3mmr]

Are there any cheap vector network analysers that actually work?

"Cheap" being like max 3-400 usd.
Intended purpose would be things like improving Z match up to maybe 100 MHz.

[hendorog]

NanoVNA is the best option for that price and frequency range IMHO.
Edit: I misread the price range, this VNA is around $50 so there may be better options for $400

These are available in lots of places, this is just a random one I found.
https://www.ebay.com/itm/NanoVNA-Vector-Network-Analyzer-HF-VHF-UHF-Antenna-Analyzer-2-8-TFT-Screen/202734684273?hash=item2f33edc871:g:bWUAAOSwnoldLTco

Google group is here
https://groups.io/g/nanovna-users

The white gecko labelled ones lack shielding. Mine is like this.
Some of the black ones are properly shielded and also apparently have a slightly better PCB layout.
This is more important over 300MHz where they are operating on harmonics of the LO. Below 300MHz any of them will be OK I expect.

[DaJMasta]

Can you deal with just one port and no transmission measurements?  There are a number of antenna analyzers that can be had for that budget and frequency range if you're only looking for single port measurements.

[Datman]

https://www.ebay.com/itm/NEW-50KHz-900MHz-Vector-Network-Analyzer-Kit-MF-HF-VHF-UHF-Antenna-2-8-Screen-H/183848389844