The sticky is at this link:
http://www.cigarasylum.com/vb/showthread.php?t=1612
Vendors come and go and also get better or worse over time. Posting in that thread about who is a good source now, esp w/ covid, would be most useful.
One thing that I will point out about cigars and hygrometers. It isn't that your cigars *must* be at some RH. Instead, you want to know at what RH, as displayed on your hygrometer(s), do your cigars smoke best at. It's all about personal preference and many have great advice, but in the end, you are going to be the one smoking them.
Hygrometers are a bit like watches. If you only have one watch, you always know what time it is. If you have more than one watch, you never know what time it is.