I see a lot of Android apps that are ad-supported (which I don't mind) that you have to pay for on iPhone/iPod. My theory is that Apple lock you in to registering a card for payment more effectively than Google, so a lower proportion of apps are actually bought via Android phones. Developers are then forced to make their apps available free and get revenue from ads instead.
If you are concerned that your favourtie iPhone apps aren't available, you will just have to do the research. I have no shortage of apps on my Note and I have never paid for one.