Flight Control HD on the iPhone is $.99, probably the most popular price point for apps, besides free of course. On the iPad, the price is $4.99, over 500% the iPhone price. Brushes costs $4.99 on the iPhone, but $9.99 on the iPad. The Consumerist looked at eight apps in total that cost $27 on the iPhone, but you'd have to fork out $53 on the iPad for the same titles.
If the apps had substantially more functionality, I'd understand it. Given the large screen, it stands to reason that some of the apps may have slightly redesigned user interfaces to take advantage of the extra real estate, but I am not sure that justifies the price increase. I would hope there is more to it than that.
As I said, prices are subject to change. We'll know more in a few days. In the mean time, you might want to look at what apps you have to have in the iPad version and be ready to cough up a few more dollars than you had originally planned.