Don't. These accounts can not be legit, and it is highly frowned upon.
7$ for a senior account? Seriously?
Why should he sell that when he could make 5x that amount in one week.
He has no signed messages.
He also uses "FOUND ADRESS" Which indicates he did not made the accounts himself, otherwise his grammar would've been something along the lines of "Adresses on Account"
I also find it quite odd that his english grammar is that bad.
"What you buying:"
Seriously? And you are selling highly trusted green accounts? Shut the fuck up.
"All sales are final". Which means you can walk to hell after you bought the account. He has 1 post. Who says he isn't going to run away with your funds?
And this is how you defeat the purpose of the trust system on this forum.