If you can't provide receipts for the MP's you're selling it'll be highly unlikely you'll be selling this many MP's.
I confirm I can sell with receipts. That's not an issue.
I am begining to think that anyone offering more than 71% for MP are scams.
People are more concerned with the large amounts of MP's. People on the forum exchange MP's for a 1:1 ratio a lot of the time. Taking 30% off just comes off out of the ordinary, it'll be hard to get someone to buy that many MP's daily because of Paypal and there reputation for chargebacks.