Just check coupons out (with price alert and history). Best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Input Noise 32dB, Frequency Range 300-3500MHz, Max Sound Output 115+/-3dB, Working Time ≤16 Hours, Material Plastic, Hearing-aid(Each One) Built-in 25mAh Rechargeable Batterys, Quantity 1 Pair, Total Harmonic Wave Distortion ≤3%, Sound Gain ≥28dB+/-5d, Current ≤2mA, Charging Time ≤6 Hours, Color Skin Color / Black / White (Optional), Voltage DC1.5V
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($40.99): BGb87cae
2. ($48.44): BG75597c
3. ($51.86): Cuponation9
put item in your cart and apply coupon code there 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): BGd7bb7a, tRaDetRaCKeR, BG791718, BGf87df9, BGHECARE1, BG4ee866, BGb7a0c3, 9OFFSUMMER
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Digital Hearing Aid Rechargeable Amplifier is here.
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)).