Just check coupons out (with price alert and history). What is best price?
Impedance 32Ω, Microphone Yes, Wearing Type In-ear, Cable Length (m) 1.25m, Wired Control Support, Model HSEJ04WM, Brand Xiaomi, Color Black, Frequency Response 20-20KHz, Net Weight (g) 15g, Plug Type Type-C
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 code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($16.99): BGAlerabatKL
2. ($16.99): BGAUDIO
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGXMTYPE, TTxBG10, BGXMTYPE2, aff7off, BGTYPE, BG3CSUM, BGTYPEC, bgssaff9, AFfbG10, BGTC001, BGXMTC30, BGXMMTC, 502C6B, BGPISTONPL, BGPiston0109, BGVDay10%off, EARSP11, BGTT10, bGhOnEy10, BGXMTYE, 13f142, BGSS10%SW, bgshOOp10, BGELIG0920, BG11SHOP, BG4BW25, BGLOAC1, BGa0b145, BG725cc4, BGBuscape01, BGb952e7, BGBRPL2, BGHOTSHOP15, BG53e9c8, BGd173b4, BGAudioVideo
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Piston Type-C Earphones.
Price records source(s): Gearbest, 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)).