You will not pay "more" for iPad apps, relatively speaking
Some screenshots have leaked from the upcoming iPad App Store, and some classic iPhone apps in their "HD" flavor are running $2.99 and $1.99, rather than $.99. Run for your lives! Of course, there's a little bit of perspective to keep in mind here: When the iPhone app store launched, many of those same apps were $4.99 or even, gasp, $9.99! Those were crazy days, kids.
The point being, relative to where the prices were at the debut of the last app store, you're actually paying less than for those same apps on the iPad. Why didn't Apple include the iWork apps in the device, rather than charge $10 a pop? Well, they were probably trying to signal to developers that a higher price point was acceptable (and maybe even preferable) for the iPad. If a majority of the apps at launch cost more than their iPhone counterparts did at launch, it would seem developers didn't get the message. Either that, or they know the ceiling of what people will pay for apps, and it's about $4.99.