Why are batteries not included anymore and where to get them from

Since the recent issues with burning Samsung Lipo batteries, it seems that postal regulations are further enforced
Having had parcels with included batteries sent back, there will be no more batteries supplied to the US. Therefore US units will come without battery and will cost 22Euro instead of 25Euro.
However you can easily order a bunch of 3.7V AA sized batteries for under 2$ each. You can get them for example from Banggood.
Just type "3.7V AA lithium" in the search field. Delivery takes up to 2 weeks to the US, 4 weeks to Europe and probably a bit longer to the rest of the World. They have a US and a Europe warehouse too for faster shipping into these regions.