I don't understand why you would want to do this. It's not the media that costs money, but the product key. If it were possible, you wouldn't save any money. Checking Microsoft's web site, I don't see any way to just purchase a key for the full project (only the upgrade).
I've not worked with Windows 8 myself, but if it's only going to be a couple of days, you could probably install the OS from your DVD, but just not activate it. If it's like Windows 7, you have 30 days to activate it. If the recipient is local, you could order the DVD and have your friend activate (or just have your friend purchase and activate it) with the new product key.