If one looked simply on the surface of things, it might appear as if the decision to issue a Gold Dollar commemorative coin for the Louisiana Purchase Exposition (LPE) was simply a matter of "next in line." The LPE's Gold Dollars - the fourth US commemorative coin program - followed the 1892-93 World's Columbian
Half Dollar depicting Christopher Columbus, the 1893 World's Columbian
Quarter Dollar featuring Queen Isabella and the 1900 Lafayette Memorial
Silver Dollar depicting General Lafayette and George Washington.
Such a conclusion, however, would be wrong.
The true reason can be found in the fact that US Gold Dollar coins had not been produced/issued since 1889, and market prices for common dates of the small gold coins (they were struck from 1849 to 1889) had risen to $2.00 or more by 1903-04. The interest in the discontinued denomination within the public led the LPE Company to select it for its commemorative coin(s). (No doubt with
some urging from Farran Zerbe, the coin dealer who was selected by the Company to promote and distribute the coins.)
The then-current market value of the regular-issue coins was a key factor in setting an issue price of $3.00 for the commemorative pieces. It was assumed that if the public was willing to pay $2.00 or more for a common date regular issue coin, it would be willing to pay $3.00 for a special, limited gold dollar issue! (They were wrong!)
Had the public not become interested in the discontinued denomination "curiosity," there's a chance that silver half dollars would have been selected by the LPE Company and a lower issue price would have been set - likely $1.00. Even absent of the gold dollar's market value increase, something tells me, however, that the ever-a-promoter Zerbe would have pushed for the Gold Dollar's selection so that he had a first-of-its-kind novelty to promote!
1903 Louisiana Purchase Exposition Gold Dollars - Jefferson and McKinley Obverses
1903 Louisiana Purchase Exposition Gold Dollars - Common Reverse
For other of my posts about commemorative coins and medals, including others about US commemorative gold coins of the classic era, see:
Commems Collection.