Account selling is bad practice in my book! Usually ends up involved in some scam or another.
As mentioned above I believe that most account trades are done for signature deals. [...]
Perhaps so; but the vast majority of signature campaigns don't require you to have positive trust - in fact, I've only ever seen one so far that required it. Yet, the OP is promoting his account specifically on the base that it has positive trust, and seeking a higher price because of this. The way I see it, whomever is willing to pay for this extra will either resell it for profit, or use it to scam - a regular, cheaper Senior Member account would do well enough for a signature campaign.
OP, please reconsider selling this account.