I just bought my 3x3 tech cotton tatonka from
http://www.trekdirect.co.uk after a quick call to check if they had stock.
Very good price (postage is included) and it arrived 2 days after the order.
At the delamere meet I used it for the first time to cover my Paradise Double hammock. It would only cover it on the diagonal, but it gave a nice amount of space. I noticed that a lot of people with the Group Buy hammocks used 3x3 tarps not on the diagonal, which I have to say I was quite jealous of (seemed to give much more usable space under the tarp).
On mine - to shed the water more efficiently, I ended up using 4 guys as well as the ridgeline.
Here's a pic (before adding the 2 extra guys)...