Capacity: 4ml, Diameter: 24mm single coil design for easy building, Thread: 510, Easy top filling, stainless steel and glass, Air holes under the coil.
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Updated:
Price history and price alert
Here is price history (for all/most countries) for Wotofo SERPENT SMM RTA Black. The lowest price was: $16.99.
Price records source(s): Gearbest
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)).