As to value and collectibility, I found this listing on the Advanced Book Exchange:
1. THE VANGUARD OF VENUS
Bartlett, Landell
Bookseller: Popeks Used and Rare Books
(Otego, NY, U.S.A.)
Bookseller Rating:
Quantity Available: 1
Price: US$ 138.00
Book Description: Experimenter Publishing Co., New York, 1928. Soft Cover. Book Condition: Near Fine. Dust Jacket Condition: No Jacket. First Edition. This vintage promotional booklet is bound in original printed self wrappers with black lettering and the logo of Amazing Stories. Cover, pages mildly browned, but clean; slight wear at top edge of front cover. This scarce title was a circulation promotion for Amazing Stories, printed by Hugo Gernsback. 24 pages; approx. 6"x8". Bookseller Inventory # P14069
Link:
http://www.abebooks.com/servlet/SearchResults?bi=0&bx=off&ds=30&recentlyadded=all&sortby=1&tn=Vanguard+of+Venus&x=0&y=0
Hope that helps Steve