The "other balancer" referred to by mithra is the Hunter GSP9700. To find a shop near you that has one, go to: www.gsp9700.com.

Before you resort to that though, make sure the tires are DYNAMICALLY balanced with weights inboard AND outboard. It is very common for shops not to use weights on the outer lip of alloy wheels because owners complain about scratching their wheels. These cars have nimble suspensions and wheels that are not dynamically balanced will vibrate, period.

Also, if the flex disk was bad enough to vibrate, you would be able to tell by a quick glance. It would be in pretty bad shape. If it looks good and wiggling it shows no slack, then it is not your problem.

Good luck,