My 2007 "small" battery was
My 2007 "small" battery was replaced 2x. The second time, about 5 years ago, I replaced it with the battery designed for the 2010-?. It is still going strong. Occasionally I forget to turn off my lights and my Prius recharges fast. Now I only have 110,000 miles.That second battery, from O'Reilly Auto Parts cost about $125, not sure where you spent $500 for a battery.