What makes u think that?
For some odd reason, the white iphone (at least in my area of the midwest) has consistantly had a higher resale value. The white iphone also "hides" scuffs and marks" better than the black one which also increases value.
plus in the countries that the iphone will not release initially, there will be high demand for the gold iphone as it is not a standard color (ie: the middle east)