Hyper Thyroid in Kitties

My 14 yr old girl Piper has been diagnosed as being in the grey area when it comes to being Hyper Thyroid. They are currently doing more tests right now to determine exactly what is going on. I have already decided that if need she will have radioiodine treatment. Just wondering if anyone if anyone had experience with this and approx how much it could cost. I am in NJ. Thanks Helen