656 USD is a lot. I pay 675 CAD as mandatory for 5 years. Though extra payments mean I'll be done at 2 and a half years assuming nothing stops me from continuing my payment schedule.
Back then, I did get about $7,000 back in credits and rebates though, which are gone now. And it is the highest trim with all the bells and whistles. Yes, it is a lot, and that's why I decided to keep my Gen 4 given my budget and very high new-Toyota prices and sinking used-Toyota prices. I think I might get a Gen 6½ Prius Prime 2032 model year, which is seven and a half years from now. Mine will be eleven years old then. Who knows, I might even get a BEV or some other car make then.