That much?????? The rare book market is very soft the last decade or more, -my thing (side) has always been as a book dealer, have many thousands of books (use to buy estate holdings which come with a lot of junk... but an extraordinary book here and there...) Mike, Bruce and Hambone did pretty damn well at those second hand prices in the current used book market (though it is very true that specialty fields like firearms collecting are fairly strong at any time... still 500-700 seems remarkable in todays market)
Good for them!