Best place ( IMO ) to buy loose 18650 cells is from the
Orbtronic website. They have the best brands and are a USA based seller. They sell Panasonic, Sony, Samsung, LG....all the best brands, both protected and unprotected. I've bought both LG and Sony 18650's and also some 26650's. All rated ( and tested by myself as well ) at the highest capacity. They even sell the newer 21 and 20700 type cells. All products shipped from Fla. Fast shipping too. Every order I placed arrived within 4 days ( east coast ). The protected cells they sell use their own protection circuit which then get the "Orbtronic label" regardless of the actual battery manufacturer. Otherwise you get the basic manufacturer's label if buying unprotected cells. Personally, I won't buy li-ion batteries from any other place.