07 Package 5 10kmiles vs New 08 model

I have been in the market for a prius for awhile now. I want to get a package 6 touring. I recently saw a used 07 package 5 touring with leather upgrade. The car has 10,500 miles on it.
The dealer will sell me this car for 24,500 dollars... when i took my car in for trade ( 2000 bmw 3 series with 200,000 miles, they offered me first 2000 then 4000 for trade )
my price for the 07 package 5 with leather seats and 10,500 miles will be 20,500 plus my trade(4000) in plus $180 dealer prep plus 5%tax.....
Is this a good deal or bad deal?