Maui had hyper t, years before the diabetes diagnosis. She had the 131 treatment and while yes it was expensive (I'm in NY metro area - everything is more $$ here), it was well worth it.
The hardest part was having to leave her there for 72 hours and not being allowed to visit. I brought her food, and old t shirt that I wore so it had the "scent of home" and it was a 24/7 place, so she was constantly monitored.
If you get it done and bring any personal items, be sure you are willing to part with them - as they will not return it to you.
The treatment takes minutes, but the wait takes days.
Aside from that and having to collect and hold onto litter for 2 weeks, before putting in trash, it was the best thing I could have done for Maui.