If you have a Target redcard (either debit or credit) you get 5% off. Target carries $50 gift cards, so you would get 10 of them and pay $450.
If you sign up for the pharmacy rewards, you get a 5% savings certificate after filling 5 prescriptions. You can use that at the same time as your redcard discount for more savings. In July, if you sign up and fill ONE prescription, you get a savings certificate mailed to you.
The redcard discount works both online and instore, but the pharmacy certificate won't give you a discount on Disney cards online - just in the store.