Developing iOS apps on Windows 7
So the bad news is that XCode is needed for its iOS Simulator as well as its Application Loader facility for actually uploading the programs to iOS devices for "real" testing. You'll need XCode for signing your apps before submitting to the App Store. Unfortunately, XCode is only available for OS X.

However, the good news is that you may be able to purchase OS X and run it in a virtual machine such as VMWare Workstation. I don't know how straightforward this is, as it is rather difficult to get OS X to run on non-Apple hardware, but a quick Google search shows that it is possible. This method would (likely) be cheaper than purchasing a new Mac, although the Mac Mini retails in the US for only $599. Some posts I've seen indicate that this may or may not be legal, others say you need OS X Server for virtualization. I'll leave the research up to you.

There are also services such as MacInCloud that allow you to rent a Mac server that you can access from Windows via remote desktop, or through your browser. Unfortunately, I don't think you'd be able to use Application Loader, as you have to physically connect the device to your computer, but it would work for development and simulation, at least.

Good luck!