Aliexpress
Click here… to search for ToolkitRC ST8 RC Servo Tester on Aliexpress
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
Coupon (54.04 USD): BGToys1
Coupon (55.25 USD): BGRCParts8
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGST810, Parts8, AFfbG10, BGST812, BGST81, BGTOOL812, BGST815, BGTRC812, BGAFF10OFF, bGhOnEy10, BGCROOT1, bgshOOp10, BgcLuBofErtA10, BGCuponation10, BGHONEY2110, BGDAVIS, Tabby20, BG1efeb0, 8BGwbg2204, tRaDetRaCKeR, pROMo8cuPoN
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for ToolkitRC ST8 RC Servo Tester? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).