How can I find out which iOS apps I've purchased were free? I know that I can see all my purchased apps in the App Store on my iPad but it doesn't give any indication of whether these are free apps or whether I paid for them.

I am in South Africa and have accounts in both the ZA and US stores. Before the ZA store had access to most apps I would buy them from the US store that I had loaded with vouchers. Unfortunately I left my iPad's store connected to the US store and "bought" many free apps there too. Now I keep the ZA store connected and apps purchased from the US store don't update unless I switch stores first.

So I want to uninstall all the free apps I purchased from the US store and re-purchase them from the ZA store, leaving only paid apps purchased from the US store installed. The problem is that once an app has been purchased the app info pages in the store no longer show the cost of the app; so how do I tell free and paid for apps apart? Not having bought the apps by credit card I have no email record of the purchases to refer to.

I rarely use the App Store functionality in iTunes (on Windows) so perhaps that holds some key to this and I will check, but in the meantime I'm hoping someone already has the answer to this.
Not something I've actually tried, but how about sign out on iTunes [store menu], then use the store as an anonymous customer? That might let you see the pricing.