Why is the latest version $50 but to renew our subscription is $100?!?
Marketing. We cannot explain it, but the renewal is often/usually more costly than just making a new purchase either from Norton or some other reputable retailer.
Most here that know about this turn off Auto Renewal and shop around for the best deal. Then enter the new product key a day or two before the old subscription expires, as you will lose any remaining time if you enter the key too early.