One thing I noticed about the WWoHP is that even though it is a theme park, the pricing for Potter items are pretty much on par with the prices of Potter items everywhere else. Potter t-shirts from WB and Hot Topic run in the $24.95 range and up same as in the park, Noble collection wands run about $30-40 from WB same as in the park, hoodies run $40-50 online from WB and Hot Topic which again is the same price in the park. They haven't really upped the price in the park against prices for similar Potter products elsewhere. Even with items such as the brooms, robes, scarves and ties they are priced pretty much the same as elsewhere.
The good thing about the WWoHP is they sell products there you can't find anywhere else and their prices are still inline with other Potter retailers.