Few people know this, but to filter an Amazon search for items sold by Amazon.com, append this parameter to a search URL:

&rh=p_6%3AATVPDKIKX0DER

Example:

https://www.amazon.com/s?k=charger&rh=p_6%3AATVPDKIKX0DER

You should now see 'Amazon.com' checked under 'Seller'.