I have no connection or profit in this company. But these are the guys I got the 26800 batteries from for only $4.75 each. These two section are probably 99% of what we here would be interested in. Some prices are much better than others some not so. I’ve ordered twice from them, once on Tuesday and shipped the next day. One order on Saturday shipped the next Monday.
https://alofthobbies.com/power/batteries/lithium-ion-individual-cells.html and
https://alofthobbies.com/power/battery-chargers.html for Xtar chargers.