You can get Geekcreit Assembled Geiger for 38.99 USD using coupon code (in Banggood). Just check coupons out (with price alert and history). What is best price?
Latest coupon and price update (UTC):
Banggood (38.99 USD)
Banggood warehouse is located in China. I’m afraid that there’s no working coupon in Banggood. Low/high price? Hmmm, price is higher than average (which is 34.99 USD right now), so better set price alert down below…
Link: Banggood product page
Price: 38.99 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGc7db29, Cuponation9, BG8ReviTrage, BGf6ca76, BGcoupon8off, BGGutscheine, TTBLACK5, BG589b2e, BG8FORMULAMX
(probably won’t work, but you can try them out)
Aliexpress
Click here… to search for Geekcreit Assembled Geiger Counter Module Miller Tube for Arduino on Aliexpress
Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for Geekcreit Assembled Geiger Counter Module Miller Tube for Arduino.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).