Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Flexible Extension Bar Length: 128mm, Color: Blue& Silver&Black, Bit length: Approx. 28mm, Driver Adapter length: Approx. 26mm, Model: RZ-S5801, Case Size: 20.5×9.5x2cm, Material: Chrome vanadium alloy steel
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($14.44): BGScrd15
2. ($15.29): BGAFF10OFF
3. ($15.29): bGhOnEy10
you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): 20tools, 502C6B, 38fdec, BGdb3b, AFfbG10, TS15prime, Tools1, Tools3, BG2020NS, BGTools65
(probably won’t work, but you can try them out)
Price history and price alert
Here is price history (for all/most countries) for RZ-S5801 58 In 1 Screwdriver Kit.
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)).