What shopping for incunabula was like in 1947, from a library ledger

With a large collection I just purchased came a ledger, 500 handwritten pages of recordings of purchases for a Northeastern Jewish College. Between the purchases of JPS and Bloch publications filed indiscriminately are some recordings that would make some of us drool.
May 13, 1947:
נביאים ראשונים שופטים ושמואל Soncino 1486 Incunabula $250
ערוך לרבי נתן בן יחיאל פיזרו 1517 $100
רמבן על התורה -משה בר נחמן גירונדי פיזרו 1514  $60
מורה נבוכים סביונתה 1553 $60
שו"ת ר דוד כהן מהרד"ך קושטנדינא 1533 $60
מחזור ברצלונה מנהג קאטאלונה שאלוניקי 1527 $40
the list goes on and on. For comparison,  see these 2 filed one after another in photos below
שות ישכיל עבדי  which was recently published at the time for $35
followed immediately by מגלת אסתר 1592 Venice for $30.
Forget about mourning on lost stock or real estate opportunities, anyone old enough to remember Harry Truman could have bought thousands of such books at these prices, many of which have had their value appreciate to over 25,000 %. Take the Ramban Pesaro for one example, I just paid a few months ago for a decent copy over 200 times the price they paid for it in 1947.