One think i must say you there is an hero account being sold at those rate, soo i really doubt you can sell your potencial senior for such price, does this account has a signed message? Reduce your price if you really do wanna to sell the account.
I can sign a message.
Are you meaning you can provide a message signed by a wallet address used in the account you are selling, or that you can sign a message to say you are selling the account?
Can you provide a BitCoin estimator on what they think the account is worth?