It is rare but the issue may have more to do with the fact that is Golden Dragon, like the 52 Virginian, does not offer much exclusivity, not enough to justify buying it for what it is. The 53 Dragon we know is one of 1277, and within this range are rare color combinations and generally the 53 Dragons are the most desirable KF not called a Darrin, a 49-50 convertible or a hardtop model.
There are rarer cars in the 9 years of production - than the 53 Dragon - but they are not more desirable. So for the 51 Golden Dragon's it is kind of like Carleton Spencer putting a licked finger up in the air and seeing which way the wind blows. It portends the 53 Dragon.
The experts might comment if the "Golden" Dragon color is unique to the 51 Dragon, or whether it could be ordered as a RPO or SPO.
Neat car, but rarity does not mean much.