It might be sold he hasn't commented on any of our questions in a couple days

Was a limited time deal. Its over now. $400 or even $500 would be an incredible deal, im just not sure the op is legit if he wont even post a pic.

Most likely the box is open if he had it unlocked.

I imagine he had to enter the unlock code in the device itself or have it flashed.

You are brand new here so I guess you would be fine using escrow? otherwise no one will even consider this offer as serious but I hope you would use escrow. Is the price final or you can negotiate on It a little? Do you have only white Samsung galaxy S5 or you also have different colors like white and other? Are those smartphones brand new from factory?