Parksavers ticket & adding park days

[theone74733]

We were planning on going to WDW for 6 days/5 nights in Nov so a 5 day park hopper ticket would work for us. I was checking Parksaver prices and a 5 day park hopper is $400. However, there is a 7 day (with 3 "free" days) park hopper ticket for $389 and a 3 day park hopper for $345. I was wondering if you could just upgrade the 3 day park hopper for another two days and that would be cheaper than getting the 7 day ticket. I think the price is $10 per additional day, but wasn't sure if that started after a certain day.

Any advice is appreciated.