Whatsminer.net is legit site (not Whatsminer.com which I have not seen any feedback on)
I purchased a new unit a couple years ago and last week purchased a used (claimed to be factory refurbished w/month warranty) Whatsminer M30.
I arrive from China in about 7 days from payment via DHL which is quite quite fast to US.

I would note that Factory Refurbished really seems to mean just that there is apparently 6 months of their original (or maybe a new 6 month warranty) but a basic air blow out of unit before power up shot a fair amount of dust and a small amount of small leafy material out. It was well packed in original box inside a secondary box. It has been running with no issues for a day now.

Most of the units are sold now with a few M30's and M31's left. They had released several batches over a couple weeks so may be more if you get on their mailing list if interested in any future lots.