at first i was curious as to what relevance the schoyen collection had to do with the Diamond Sutra, so i wiki'd it. http://en.wikipedia.org/wiki/Schoyen_Collection
"Some ancient Buddhist manuscripts, taken from Afghanistan to preserve them from the Taliban." is this what is in the book?
i wouldn't be surprised if copies of the Diamond Sutra were found there, considering the long history of Buddhism in the area, even going as far as Greece for example. the wiki on greco buddhism on wikipedia is an interesting read.
but wasn't the Diamond Sutra the first Chinese Sutra written? i could be wrong, i am quite often.
i know how books appreciate in value, some books i have, are sometimes 3 times more expensive on amazon, then i go find another publisher in another country and find it at normal price. for example i recall seeing The Kamasutra of Vatsyayana for 150$ new on amazon, then went to a publishing company in india and it was 50$ and i got 25% off and free shipping due to the xmas holiday.
just thought i'd share.