Marco, I don't know if anyone cares where you get the dvd for Vista Gold.
But the cost of a product key is simply the price of the retail box anyway.
You might as well buy the retail box when it goes on sale. According to a
recent article by Mary Jo Foley, if you buy Ultimate (I assume full edition)
you can then use Anytime Upgrade to purchase one or two additional licenses
at a fraction of the full retail cost.