Depending on which product key you have, and your current geography, I may know of something that could work in your favor...
I work in the School of IT at the local community college. We have a licensing agreement with Microsoft which lets our students get free copies of Windows, amongst other things. The students check out the discs and are allowed to make copies of said discs. It's part of the Microsoft Developer Network Academic Alliance, or MSDNAA for short. If you have an MSDNAA affiliated college in your area, if you were to explain the situation, they might be willing to let you make a copy of their disc. I'd bring in a blank DVD or three to sweeten the deal. Also, you'd need to make sure your product key matches the version of windows that they have. For example, my college has Windows 7 Professional, which won't work with home basic or home premium product keys. You get the idea.
Either way, best of luck to ya.