Roughly 6
Why not use an exchange to cash them out? Seems much easier if you just want to be done with it?
I. What's the markup rate,
II. what's the payment processor you want to use? (Bank transfer/SEPA/paypal?),
III. will you use escrow?
IV. and, can you sign a message proving you have 6 BTC, or not? (If you can't, you're just wasting your own time here.)