As far as I know - there is no such thing. The 'small charge' is
basically (I would assume) the full price of the OS - if such a
thing does exist. I could be incorrect - but without proof (still
have the invoice for the purchase?) - there's not much anyone
could do for you.
After all - it is not difficult AT ALL to get a copy of the CD...
It's the CD Key that matters.
Microsoft has no idea you activated/registered by now. (Nor did
they likely ever have a long-term record of it.) If you had just
lost the media
itself - you might be able to use this method:
How to Replace Lost, Broken, or Missing Microsoft Software or
Hardware
http://support.microsoft.com/?kbid=326246