Creality 3D 310x310mm Flexible Cmagnet Build Surface Plate [EU] (Banggood, Aliexpress: Size: 310*310mm, Applications: For CR-10/CR-10S (the best price with coupon)).
You can create price alert here, copy coupons and view price history. You probably want to know what is the 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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in Europe 
. I don’t really know if this price is reasonable, coz there’s no price history in my DB. Only one coupon available!
Link: Banggood product page
1. ($18.13): ADMITAD2212
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGHONEY2110, 13f142, 6GSGIT, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, hoNEYbGdeAlS, BGJUNEGSG9, BG8ReviTrage, Cuponation9, BGcoupon8off, BGGutscheine, BG8OFFCOUPON, TTBLACK5
(you can check these old coupons out, but these probably won’t work)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Creality 3D 310x310mm Flexible Cmagnet Build Surface Plate ($-3)
Price history and price alert
Not enough data to show price history chart… $16.99 is the only recorded price. It was not cheaper than that since we have saved it in DB.
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)).