2001 transmission problem

I realize this may have been addressed before in previous threads but that was then (2010) and this is now. I began hearing a whining/humming sound just a couple of days ago esp when hitting 45mph and then would notice as I took my foot off of gas. I had hoped it was either tire or bearing related, but Toyota tried for over an hour and finally determined it was transmission related..a new transaxle assy etc would cost total of 6500$. However they said they did not think I had to do anything right now as everything is well lubricated..they even thought it could remain the way it is for a year to two. My Prius has 180,000miles on it. Should I attempt to find a salvage transaxle and risk having it put in? Or should I cut my losses and giver up?