You will need to install a user script manager extension to install this script.
If you order from a third party on Amazon you won't have the advantages like customer service for refunds or your order counting to the minimum order value. Higher risk to fall for scammers, fakes and bad service.
Done with that, now you will be warned if the product comes from a reseller.
Sold and shipped by Amazon = green
Everything else = pink
You can easily define and save (will not be overwritten by updates) your own color preferences in the source code (all valid CSS colors like HEX, HTML-keyword, HSL, RGBA are allowed).