Here in Toronto I've been quoted virtually the exact same price for a 2004 Prius (full Canadian option package) as I was for the 2001 Prius (Canadian base model - which was the only available model). Same insurance company and same policy options.
I just got a quote from State Farm. The Prius will be $10 more for 6 months than the Altima it is replacing. I would consider this a wash.