I don't want to judge you as a scammer, but we have a few reasons for suspect you (as peoples said above). A bit suspicious when you have a key to open the treasure box, and then you sell those key instead of tried to open the box. 
That's better, then go for it.
I have been asked about possibility of escrowed deal through bitrated service, I have no problem with that as long as the intermediary is a person whom both sides trust.
That's better, then go for it.