According to my DB the lowest price is 13.59 USD for Extreme Pro SD Card (in Banggood). Basically copy coupon, view price history or create e-mail price alert. What is best price?
Latest coupon and price update (UTC):
Banggood (13.59 USD)
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood. What about the price? Well, this price is higher than average price (12.85 USD)
Link: Banggood product page
Price: 13.59 USD
Old coupons (from the oldest to the newest): BG79911a, BG155fb9, BG589b2e
(probably won’t work, but you can try them out)
Aliexpress
Click here… to search for Extreme Pro SD Card 128GB on Aliexpress
Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for Extreme Pro SD Card 128GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).