AMH levels -- Has anyone had this tested?

[Hopeful at 40]

I recently went through some new testing... and the IVF center measured my AMH levels. I did some research, and it seems that this marker is a better predictor than FSH many times. It correlates with resting follicle count, and doesn't vary during the cycle. However, it is an expensive blood test -- and many facilities don't offer it. Has anyone had this tested? Does anyone know what range is considered normal? borderline? or out of range? I'd love to learn more about this -- but the internet seems limited in the amount of information available on this subject. Thanks.