Cheaper to buy new 360 than renew!

My Norton 360 standard is due for auto renewal in December BUT a new 360 standard is only £24.99 to buy! So I can save £40 by buying a new one and then run a backup to save all my files…am I correct and why do norton charge £64.99 for renewal …but only £24.99 for new customers?. Doesn’t make any sense.