Aliexpress
Click here… to search for 3mm Magnetic Ball Toy 216Pcs on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Price history and price alert
Here is price history (for all/most countries) for 3mm Magnetic Ball Toy 216Pcs.
Price records source(s): Gearbest
Click on image to enlarge. 
You can set price alert (for Banggood).