I bought the corded one which arrived quite quickly. Then the cordless version became available again and I bought it at the good price (USD 21). It arrived today when I was advised the earliest date of delivery is the 21st :-)
Very good mouse. Now I alternate between this mouse and my Logitech to minimize the risk of RSI.
Update: October 4, 2017
A year later this Anker mouse is limping. The scroll wheel no longer work properly. When I scroll down it sometimes moves up. I wanted to get a replacement but they are all over priced on eBay. So now I am trying my luck with something else.
I really wore this thing out through heavy use.