Go down and check coupons out. Remember to check price history if it is available. Best price?
Open-source hardware, USB-powered, Software-controlled antenna port power (50 mA at 3.3 V), 1 MHz to 6 GHz operating frequency, Compatible with GNU Radio / SDR# / and more, Internal pin headers for expansion, Software-configurable RX and TX gain and baseband filter, Hi-Speed USB 2.0, Up to 20 million samples per second, Convenient buttons for programming, Half-duplex transceiver, 8-bit quadrature samples (8-bit I and 8-bit Q), SMA female antenna connector, SMA female clock input and output for synchronization
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Coupons for HackRF One 1MHz to 6GHz USB Radio Platform SDR RTL? Nope, there’re no coupons in Banggood.
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!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGa380c5, MVC8SPRING, BGJUNEGSG9, Cuponation9, COUPONSDE1wk, BgGoodie9, BGcoupon8off, BGGutscheine, BGTOOS729
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for HackRF One 1MHz to 6GHz USB Radio Platform SDR RTL.
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)).