According to my DB the lowest price is $11.99 for Celestial Demonstrator Three Ball Electric Sun Earth Moon Model (in Banggood). You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Celestial Demonstrator Three Ball Electric Sun Earth Moon Model Pupils Handmade Scientific Experimental Equipment Education Toys
Latest price update (UTC time):
Banggood ($11.99)
Banggood warehouse is located in China. I couldn’t find any coupon for this product on latest product update. Good or bad price? Well, this price is higher than average price ($6.29)
Link: Banggood product page
Price: $11.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for Celestial Demonstrator Three Ball Electric Sun Earth Moon Model? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
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)).