I have a Mavic Open 4 CD/Mavic 500 wheelset built last year, been used for 50 miles and stunning.
They won't be cheap as I would like my money back for them if you are interested
I rarely see wheelsets sold with DoubleButted spokes. Most of the time it's just plain gauge with brass nipples. Why? Most of the people who are senisble enough to opt for the handbuilt, rather than the factory wheels, are always after alloy nipples and DB spokes. At least those who I know.