Leopard server however CAN be run under emulation and can be used for desktop purposes. If you're interested in option 1) I would suggest starting at Insanelymac and reading the OSx86 sections.
I do think you should consider whether the time you will invest is going to be worth the money you will save though.
The first route requires modifying (or using a pre-modified) image of Leopard that can be installed on a regular PC.
This is not as hard as you would think, although your success/effort ratio will depend upon how closely the hardware in your PC matches that in Mac hardware - e.g.
Don't just give a one-line answer; explain why your answer is right, ideally with citations.
Are there plans for an i Phone SDK version for Windows?
If you have a jailbroken i Phone, you can install the iphone-gcc toolchain onto the i Phone through Cydia and that way you can just compilie the apps on the i Phone.
Apps that are developed this way can still be submitted to the App Store.
You don't need much horse power to run the SDK and you can always sell it on later if you decide to stop development or buy a better Mac.
Update: You cannot create a Mac OS X Client virtual machine for OS X 10.6 and earlier.