Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (13.50 USD): BGROBOT10
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): 13f142, BANGGOODSD, 00c906, ADMITAD2212, 2022ACTIESNL, Tabby20
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Steam DIY Bubble Blister Robot Machine Kit.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).