Question for Trade dollar & pattern specialists

In 1873 and 74 the Philadelphia Mint Medal Department sold sets of 6 different pattern Trade dollar designs. According to the Chapman Bros. 1895 Winsor catalog (lot 1135, p.69), the sets were priced at $30 each. However, correspondence from Director Linderman states the patterns were to cost $3.00 each - or half of what the Chapman's state. Which is correct, if either?
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Is this a trick question, or just click bait?
How does one get a hater to stop hating?
I can be reached at evillageprowler@gmail.com
I have no idea. Just throwing out WAGS, could the $30 price have been for one six-piece set of both years?
Not a trick question.
All the sets were dated 1873, but they were sold in both years.
The only evidence quoted comes from the Chapman catalog. So far I have not found an announcement in hobby publications of the period, nor has a mint "flyer" or "circular letter" shown up.
The silver patterns were priced at $2.50 each or $15 for the set; prices in paper currency.
The dies were destroyed in April 1874 and a request for a set from Francis E. Spinner in
June could not be filled. The Trade Dollar pattern matter was published in the summer
issue of the 2017 Gobrecht Journal. At least 50 sets were sold.
Thanks!
PS: Very nice article!
According to the Trade dollar pattern set article by Robert W. Julian, the sets contained 6 different pattern pieces and cost $15 for the set. Individual patterns were sold for $2.50 each. There's a lot more information in the article, so interested members might want to purchase a copy of the Gobrecht Journal.