Sorry, I do not know of any US based store that has them. I buy most of my stuff from Fasttech in China. Takes a week or two to get it but the prices are good and Fasttech has a good rep for customer service. They still have a couple of the mini V3 clones listed. If you are just looking at form factor, look for a KF Prime clone instead. They are about the same size, same design, but with a better airflow control. I'm using one right now (but I bought it from Fasttech).
Yes, but be careful to check the reviews. I have several, and SXK an YFTK were the only ones that were really worth using. When FT no longer had them, I got a no-name from them, and a Lie Feng from another site, and they were pretty bad. That's when I decided not to buy any more no-name clones.
Also, I loved KM3's, but never could get along with the Prime. A lot of people love them, but they do deliver a different vape from the KM3. I was seriously disappointed, and really wanted to like that one. But no matter how I built it, I couldn't get a decent TH out of it. Reminded me of the Ares and KM5 mini, so I gave it away.