It was such a big event in Aurelia's life I had to pursue the question although told the answer was confidential, none of my business, they didn't know or they wouldn't say.
Aurelia Plath was paid $190,000 for her daughter Sylvia's letters and other items now in the Sylvia Plath mss. at the Lilly Library at Indiana University at Bloomington.
The sale, through a dealer, was completed in March 1977.
$190,000 in 1977 is worth in 2024 either $985,150 or $1,101,400. In either case, a cool million.
Worth it, for Sylvia's letters home, early short stories, diaries, paintings, and memorabilia: more than 3,000 items. Aurelia opened the Lilly collection to the public having decided what the public should see. I think she removed Sylvia's "lost" short stories
"The Trouble-Making Mother" and "The Mummy." But let's admire Aurelia's amazing foresight in amassing and preserving for 45 years this dazzling literary trove and making it available. Many a scholar has made money from it.
Aurelia's writings and correspondence never mention meeting an appraiser or dealer, or negotiations over the price and dealer's fee.
Aurelia -- in 1977, age 70 -- for tax reasons divided the $190,000 into 10 annual payments. [1]
I heard more than once that the dealer held back some items and sold them.
Aurelia at a later time donated further Plath materials to the Lilly Library's Sylvia Plath archive.
[1] In 1977 the federal tax rate for a single filer with a taxable income of $19,000 was 34 percent. TaxFoundation.org.