Some other good sources:
-- Cadbury's chocolate bars come in a gold foil that replicates the yellowy-golden color you find on a lot of gold-insulated spacecraft. (And I like the foil on the Rollo candies for replicating the Mylar that is a bit more reddish in color.)
-- Also, be on the lookout for those foil "emergency" blankets (like the ones used by marathon runners) because they can be a good source of gold foil. And one blanket will last a lifetime.
-- Check out your local florist or balloon shop for Mylar helium balloons. Some of them are gold in color. I found one shop that had plain gold and silver balloons (with no "Happy 40th Birthday" lettering or anything...) and I was able to buy a couple of each.
And yes, that is a GREAT looking diorama....