Probably the replica, but really, collectors are not interested in them. The gold ones have almost no real gold, such a thin layer that it would take thousands of them to get a measurable amount. And who wants a replica stamp? Collectors want the real thing, not a fake.
A commercially produced First Day Covers of standard commemoratives like the Alaska statehood stamp are typically worth a dollar or two. They can be purchased for on eBay or through dealers. Higher value stamps, or specific cachet makers are worth more. A specialized catalog will list the value of a cachet or un-cacheted cover.
There is very little value to these replicas. It is a layer an atom or two thick on aluminum. There is little extra value to these replicas and stamp collectors typically do not want them in their collections.
I don't think that these replica worth more than their value of metal. Actually, the value of silver is around 20 $ for an ounce troy or 31 grams.
That would be Scott number US 1124. A full sheet of these stamps has a catalog value of $11.00.
not much it is a replica after all
That is Scott number US 942 issued in 1946. It has a minimal value and can be purchased for 50 cents in mint condition and 15 cents used.
I mail my letters with stamps from the 60's. Only high denominations and other oddities from this era can bring any value to the stamps. Use it as postage.
It is worth the original cost of the stamp.
If it is a replica, not much. The only value in replica currency is the materials it is made out of, for an example a silver seated liberty quarter replica would be worth no more than its silver content, regardless of what date it said on the coin because it is a replica.
Scott #938 Most used US postage stamps are worth 20 cents, the minimum amount required to catalog and stock the stamps. Unused will always be worth at least their face value and this Mint stamp has a catalog value of 20 cents. Special cancellations and different values are likely to be worth more. Consult a postage stamp catalog, usually available at your local library for exact identification and catalog values.
A stamp is worth more unused