excavator undercarriage question?

Went to view an excavator today with my buddy. The machine ran great and seemed to function flawlessly, however when I looked at the sprockets, they were quite pointed and a few had broken off. 

My buddy who knows more about machinery than I do, said it’s not an issue since I won’t be using it for heavy work. From what I have read however, it seems when one piece of the undercarriage is that worn, it’s time to replace the whole thing. This is a 98 Hyundai 130 price is 30k. 

I’m wondering if that means the machine is in immediate replacement of the undercarriage and what the cost would be for that type of machine. I don’t want to double my cost..

Thanks in advance for the advice!