First Trek?

I’m looking on marketplace right now for my first mountain bike. I’m thinking of a marlin 6.

Ive seen $600 range on fb market place. Is this overpriced? Here are 2 that i found.

I appreciate all the help!

I’m coming off of a beach cruiser i paid $5 for at a garage sale so honestly anything would be an upgrade. I’m hoping to hit some trails and maybe do some 50 miles roundtrip? Thanks again!