Aliexpress
Click here… to search for FlipSky Mini TS100 Soldering Iron on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
Coupon (43.06 USD): BGRCParts8
(CouponsFromChina.com tip: you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): BGFlipskyTS100, BGRCPART, 502C6B, AFfbG10, BGCITYADS2019, BGVDay10%off, BG10PARTS, Parts8, BGCityadsRC8, Tabby20
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for FlipSky Mini TS100 Soldering Iron.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).