Cover 2600mAh Variable Voltage E-Cigarette Battery (2-Pack)

https://www.fasttech.com/products/1824801

Just ordered this for 30 Dollars works out £19.81 GBP so not bad for a 2 pack.

Others seem to like them http://allaboute-cigarettes.proboard...mah-battery-18

and going for £18.99 for one on Ebay

http://www.ebay.co.uk/itm/CLOVER-260...item4189c5a690

Will let you know how they fare once they arrive from Hong Kong.

Not sure how long that will be.