I've also received around ~10 of these same emails offering increasing prices to remove my review.

Maybe this is a good investment opportunity? I'm joking, but they did offer me almost twice the price of the product itself, which is interesting.

Something also curious is that the seller initially sent emails starting with with "Hi, [my sister's name]". Her name was not associated with my amazon account at all, and definitely not the name shown on the amazon review. I wonder where they are retrieving the names from for this.