I think we should all put in and market them.
I doubt they will be reproduced. As soon as they are, they will not be worth much mnore than what the new 67-77 caps sell for.
The one year, one model makes it a very limited market which will not likely justify the tooling cost compared to the 66-77 caps which were also used on many other models over the years.
It is a simple supply and demand issue. Not all that many years ago, relatively few thought totally stock Broncos were cool, and wanted to cut, lift, add custom wheels, etc. so these caps were not worth but $10-$20 each. Now, many have come to appreciate the retro and classic look they provide or want to do authentic restorations, so the price has shot up since there are not many nice ones (or even not so nice ones) left out there.
It took me the better parts of 20 years to get the 2 dozen plus I had, which I sold some of for the first time this year. I started looking again, and was able to score a few more at swap meets this summer.