Random thought I had with the possibility of a palladium proof. How about nice set from the mint with gold, silver, platinum, and palladium eagles? Maybe reverse proof?
I'm not sure if it would sell well enough to mix 4 metals as a set. Seems most stick to one or two. Actually I don't know really anyone that seeks out just platinum or palladium coins.
I would like to see a Silver Eagle and Palladium Eagle 2-piece set in ultra-high relief. The shine of the silver would be a great contrast to the matte of the palladium. Palladium does not shine like silver and is more of a charcoal color, so it would look interesting next to a highly-polished silver coin. A 1-ouncer of each would be good. The set would be about $800.00-plus though. I wouldn't do gold or platinum with palladium unless those coins were 1/2 ounce or less, as the set would be very expensive otherwise.
Not much interest in this idea eh? The mint did it in '97 to coincide with the release of the platinum eagle. I would not be surprised to see it again if a palladium eagle becomes a reality. http://www.apmex.com/Product/14069/...rican_Eagle_Set___Impressions_of_Liberty.aspx