100us-2900us@33-1000Hz @S1-S4, 5.8-8.4V@MAX 4A(S1-S4), Output Signal: , Main Output Voltage: 5.0-28.0V@MAX 10A, P1 Button: 1000-2000us @P1, Product Size: 96*68*26mm Approx., Net Weight(Approx): 140g, PPM 8CH @S5, Load(max): 100W, Display: 2.4″ TFT RGB LCD Screen(320*240 resolution), Micro USB: [email protected], Packing Size: 105*80*45mm Approx., Gross Weight(Approx): 160g, 5.0-8.4V@MAX 2A(S1-S4), SBUS 16CH @S5, Channel: 8CH Output, Signal Output Voltage: , Input Voltage: 7.0-28.0V@MAX 10A, PWM 500us-2500us @S5.
Check coupons or create price alert down below. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($54.04): BGToys1
2. ($55.25): BGRCParts8
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
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
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for ToolkitRC ST8 RC Servo Tester. The lowest price was: $39.99.
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)).