He's eaten string before and needed SURGERY? PLEASE find a box with a lid - even a shoe box - and find and put EVERY hair elastic, toy, rubber band, etc, into it. Search in places that kitty can get to but you can't - behind furniture, etc.

I hope you are lucky this time, I really do. But you have to do EVERYTHING you can to keep this from happening again. It's not only the money...it could be fatal for kitty to swallow the wrong thing.

Good luck, and follow CatLady's advice. She knows very well what she is talking about.