Size: 77x44x11mm, Item name: 7.4V 2000mAh Lipo Battery, Weight: 82g.
You can create price alert here, copy coupons and view price history. Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it?
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGDAVIS, Parts8, BGradio9, BG70e5fc, BGGAL8
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for 7.4V 2S 2000mAh 8C Lipo RC Battery? There we go. The lowest price was: $14.99.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).