I mean, you can get the HP Chromebook 13 with 16GB of RAM.. but not for $300.
Appears to be 500 dollars new on best buy website, so what would make you think that 300 dollars is not possible?
16gb of ram is around 140 dollars.
Chromebooks are disappointing because they can have great hardware but you need to jump though hoops to install any real software, and even that's sketchy depending on the model.