Am I understanding this deal correctly?

[Patrick Britton]

I am looking at buying a performing note in Fresno, CA.  Outstanding balance is 26k and purchase price would also be $26k.  House value is 175k.  Payment amount is about $450/month.  

If I purchase this note for $26,000, I will receive $450/month, right?  This means the return is over 20% since $450/month is $5,400 a year.  Yes, I know this note has only a few years left (2025), but 20% with so much equity seems pretty decent.  Am I missing something?