There was a gold city bag produced, think it was a limited edition, maybe in the UK. Decophile (I think it is her!) has one. Look through the modeling pics...
The only GOLD B-Bag was a special edition from Selfridges for the 2006 Holiday season ONLY! They are extremely rare, and I think Decophile is the only PF member that has one (we all allowed to LUST after it!!).
On occasion, Balenciaga strikes up a deal with one of the bigger retailers of their goods (they have done the same with Barneys in the past).