There's a blue Z4M Roadster MY 2006 for sale now in Constanta, Romania with a mileage of only about 2.000 Km (~ 1250 miles).
If sounds hard to believe, but it seems to be true. A friend of mine checked it out about 10 days ago and he found no reason to doubt the mileage.
However, he noticed that the vehicle was not stored in best conditions (e.g. the rubber top edge of the windshield is cracked, probably due to sun exposure).
The car is now owned by a local Mercedes dealer (probably a trade-in).
Here's a link:
http://www.autovit.ro/bmw-z4-C24391567.html