Just check coupons out (with price alert and history). Let’s see what best price is ATM.
Brand：Lintratek, Size: 130x100x200m, Frequency: 900MHz, Working temperature: -10c~550, Power supply: DC5V1.5A, Gain: 60±2dB, Model Number: KW13A-GSM, Weight: <0.3KG, Output power: 13±2dbm, Coverage: About 50-200㎡ / without barrier
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):
Banggood
Banggood warehouse is located in China. I am tired of searching coupons, but I found one for you…
Link: Banggood product page
1. ($69.51): BGWSCYT1
this code has to be applied in your cart 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): 2022ACTIESNL, Terence, 2203ActiesNL, BG1eb3ac, BG1efeb0, 8Couponsde, tRaDetRaCKeR, 8wEbgaInS5, hoNEYbGdeAlS, BGJUNEGSG9
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Lintratek KW13A-GSM Wireless Network Signal Booster LTE 2G 3G 4G.
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)).