Hey, don't give in! iPhone dev is like a game in itself. "Level 1 Complete" is the writing of the software. You've now progressed to the next level, Marketting.
When Apple sent you the 'Ready for Sale' email did you remember to edit your release date to the current date? If not your app would probably have been a couple of pages back which means not many people will see it and low sales.
Have you seen this link:
9 Places To Publicize Your iPhone App
If your App will only work on 2.2 then you have probably limited your market. I'd also go for a Lite version putting a link somewhere on the app to your full version.
Best of luck
Ivan