The reason you don't see concise answers is because $300 is mid-point between the $200 starter detectors and the $400 machines with ground balancing.
Ground balancing tunes the detector the soil at the site you want to hunt and reduces ghost responses from minerals and helps the detector find deeper targets. Nice, but not required.
If you don't already have a Garret ProPointer pinpointer ($127) you definitely should get one for land hunting, locating targets in a hole can be a major pita without a pinpointer and the ProPointer is a standard go-to.
If you need to stay under the $300 total then get a Tesoro Compadre ($160) (this machine has it's own religion), and the ProPointer.
If you can go somewhat over the $300 then a Fisher F2 ($199) or a Garrett Ace 250 ($212). Plus the ProPointer. Watch some youtube videos of the 3 detectors to help decide what looks best to you.
Remember that buying a used detector may or may not have a warranty, Garret allows warranty transfers, Fisher and Tesoro do not. Buying a new Tesoro comes with a lifetime warranty. Navigating used detector choices get's more complicated if you want to make a smart buy, so it's iffy as a beginner.
Good luck!