My question involves collection proceedings in the State of Wisconsin.

I was a cosigner on a private student loan through a nationwide bank approximately three years ago. The borrower has since left the state, changed phone numbers, email addresses, etc. I have no ability to contact this person.
I recently received calls from a collection agency stating that the loan was in default. I have perfect credit outside of this (mistake?!) and the ability to pay off the balance ($2,500), so I did so to prevent further harm to my credit.
My question is, what are my legal options in recovering the balance I paid off? The person on the phone from the agency said I had the option of filing in small claims court. Is it worth the risk? What recommendations do you have for me?

Thank you.