Right now the best price with coupon code for 2 Transmitters with 12V 4CH Channel Relay RF is $8.99 (in Banggood). Just check coupons out (with price alert and history). What is best price?
Remote Distance: 30M, Receiver sensitivity: 105dB, Operating Voltage: DC 12V, Receiving frequency: 443.92MHz, Max load current: 20A, Frequency: 315mhz, Operating Current: 13 mAh
Latest coupon and price update (UTC):
Banggood ($8.99)
Banggood warehouse is located in China. Coupons for 2 Transmitters with 12V 4CH Channel Relay RF? Nope, there’re no coupons in Banggood. You probably want to know if this is a good price. This price is great, coz it’s the lowest in CouponsFromChina database!
Link: Banggood product page
Price: $8.99
This is the best price ever noted in my database!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG1d6233, BG00c906, BG589b2e, BGET10
(you can check these old coupons out, but these probably won’t work)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for 2 Transmitters with 12V 4CH Channel Relay RF.
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)).