According to my DB the lowest price is $29.99 for DIY Science Education Assembly Engineering Excavator (in Banggood). Go down and check coupons out. Remember to check price history if it is available. Best price?
Latest coupon and price update (UTC):
DIY Science And Education Assembly Engineering Team Hydraulic Power Crawler Excavator Bulldozer Puzzle STEM Toys
Banggood ($29.99)
Banggood warehouse is located in China. Coupons for DIY Science Education Assembly Engineering Excavator? Nope, there’re no coupons in Banggood. Price? Hmmm, price is higher than average (which is $24.02 right now), so better set price alert down below…
Link: Banggood product page
Price: $29.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
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 DIY Science Education Assembly Engineering Excavator? 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)).