@Andrew S sounds like a great trip! Good point on these in shop tasting sessions. If you do the math those are good opportunities to taste otherwise unaffordable stuff to form a more educated opinion.
Quite common for higher end Yancha/Dancong in China.
In Taiwan usually tea sampling is free, although it might take some luck and longer relationships to get to try some premium stuff. Only ever heard of paid-sampling of a high level Oriental beauty shop and of course of samplings of rare old teas and some high profile event with supposedly Chen Ah Qiao made Dongding(which was in all likelihood fake nonetheless).
Looking forward to read your in-depth report!
Your day in tea
@Andrew S, that sounds like a wonderful tea adventure! As someone who also doesn't speak Chinese, it's encouraging that you were able to communicate with vendors. I also look forward to hearing more about your finds in Taiwan.