I have used Undercovertourist.com at least 5 times. The tickets are exactly what you pay for and I was able to upgrade a park hopper to a annual pass without any problems. Make sure you sign up for the Mousesavers.com newsletter. There is sometimes an additional discount. While it may only be a $2-$3 savings, if you are buying multiple tickets, it adds up.
To the OP, you may want to look into purchasing your tickets ASAP. In the event that ticket prices go up, you have already purchased your tickets at the "old" price.
An 8 day adult park hopper is $292.95 from Undercovertourist.com
An 8 day adult park hopper is $307.79 from Disney if you pick it up at the park
Quite a savings if you ask me