I looked in to the Hard Rock for my trip later this month. I want to say that even with the Florida resident discount the rate was $200 - $300 a night. Really steep IMO. I know it has the fast pass benefit but wish I could have found it a bit more reasonable. Unless someone here knows something I don't about getting a better summer rate?
I believe the UNI site will also show you deals (tickets and room) at partner (off site) hotels that might have lower rates and still include early entry for Potter phase one stuff at IOA.
One thing to consider about staying on-site is what the value of the Express Pass is to you. Consider that it is for everyone staying in the room and that it is for each day of your stay.