The people from Banggood were kind enough to provide me with some coupon codes valids through 2019.
The coupon codes are valid in different categories and you can save up to 15% with the following codes. You just need to fill them into the Coupon field on the checkout page.
Coupon codes are not valid for promo items.
Coupon code e2bcea gives you 15% off of products in a lot of different categories including whoops like the Mobula7, FPV cameras and googles like the Fatshark HDO’s - meaning you can get the HDO’s for just $424.99. Batteries like the GNB, 2S 300mAh or the ISDT Q6 300W battery charger are also available for 15% off.
Be careful, you can use this code only once per account, so make sure your order is worth it!
in case the above coupon code does not provide any benefits, you can try rchobbies8 which gives you 8% off or toyho for 7% off.
Unfortunately it is not always clear on what items the codes will work, so I suggest to always try the highest coupon code and if this does not apply, then the one below it. Sometimes it makes sense to split one order in multiple orders to apply different codes on different items, since you can only apply one code per order.