I know nothing about this book - perhaps the informed can help the uniformed with an explanation for why this mid-1980's reprint of an innocuous looking children's mystery series book sold for over $400 on eBay. The seller provided ample information, so maybe the reason is as explained in the auction. Still, wouldn't have thought the demand would be so high.
Item 290555916824 sold for $415 on April 21, 2011
THREE INVESTIGATORS #17 MYSTERY SINGING SERPENT ADRAGNA
"THREE INVESTIGATORS (formerly "Alfred Hitchcock and the Three Investigators") #17 - THE MYSTERY OF THE SINGING SERPENT by M. V. CAREY, published by Random House, copyright 1972, circa mid-1980s printing, Gibraltar Library Binding, white endpapers, illustrated front board with Robert Adragna cover art.
THIS BOOK WAS ONE OF ONLY 8 OF THE ORIGINAL #1-#28 THREE INVESTIGATORS BOOKS THAT WAS REISSUED IN THE MID-1980s WITH THE REVISED ROBERT ADRANGA COVER ART - THERE WERE LIKELY ONE OR MAYBE TWO PRINTINGS WITH THIS COVER ART AND THESE WERE ONLY SOLD TO FILL LIBRARY ORDERS - VERY RARE HARDCOVER EDITION - ONLY SOLD TO LIBRARIES. STARTING WITH THREE INVESTIGATORS #29 IN 1979, RANDOM HOUSE ONLY SOLD RETAIL THREE INVESTIGATORS BOOKS IN PAPERBACK-ONLY FORMAT (THE LAST TRADE HARDCOVER EDITION SOLD TO THE PUBLIC WAS #28). THE HARDCOVER EDITION WAS ONLY MADE WITH RE-ENFORCED HINGES (I.E. "GIBRALTAR LIBRARY BINDING") AND SOLD EXCLUSIVELY TO SCHOOL LIBRARIES. AS A RESULT VIRTUALLY EVERY SINGLE HARDCOVER COPY OF THIS BOOK THAT IS FOR SALE ONLY EXISTS AS A DISCARDED EX-LIBRARY BOOK. THE EIGHT "ADRAGNA" HARDCOVERS VERY RARELY COME UP FOR SALE - THEY ARE MUCH RARER THAN THE HCs OF #29-#43 (I DON'T THINK I HAVE HAD ONE FOR SALE IN OVER A YEAR).
Book has no ex-library markings/stamps.stickers/card pocket to title page, copyright page, rear endpaper or outer page edges, slight paper residue to ffe, couple of creased page corners, no spine lean, no foxing/drop stains to outer page edges (slight dust soiling only), endpapers are otherwise clean and free from markings/tape residue, no former owner's markings or used bookseller stamps/stickers inside, no wear to board edges, slight wear to board corners and spine tips, no soiling or staining, no dust rubbing to rear cover, no color tearing to boards or spine of note, no spine sun fade (common defect with this book), no bumped board corners.
Note: This book comes protected by a removable clear Brodart book cover (cover is not taped to book - it can be simply slipped off if desired) which prevents further rubbing/soiling damage to the outer boards. Any white marks/glare lines in the photo are simply glare from the flatbed scanner reacting to this Brodart cover (and are not actual defects with the book).
Overall a VG+ book of a rare "Adragna" hardcover printing Three Investigators book. THIS IS ONE OF THE LAST OF THE ORIGINAL 43 THREE INVESTIGATOR HARDCOVERS AND IS NEVER FOUND WITHOUT SIGNIFICANT WEAR AND EX-LIBRARY MARKINGS. I have a number of other hardcover and paperback Three Investigator books up for auction on ebay - just click on the 'see other items' link to the right of the picture."