Buy now or forever be priced out of a crappy operating system. The price of operating systems only goes up. You could buy a license today and sell it after Jan 31 for a profit! Oh shit, you actually could do that. Forget I said that.
^ I don't know, but the 'oem' version that home builders can use is currently cheaper than $200, but much >> $40.
If you upgrade to windows 8, it gives you an option for a basically fresh install. It does not reformat, and keeps your old files in a single folder. But, I think it gives you a fresh registry with no old program settings or crap like that.
^ Dan, for that reason, I think you will be able to get licenses much cheaper than $200 for a while on ebay.