There is a big slump for sales of vintage baseballs right now on eBay. The YMCA ball is a nice addition, and I was even looking for one for my book to add in the "War Balls" section. But you'll never get over $1000.00 for it right now, its a neat ball but lacking the Spalding logo on top and because it was made for the YMCA, people know it wasn't intended for use in the big leagues so it gets an unfair status.
The ball itself however dates to 1920-1925, not 1917. I would put it up for like $899 or best offer and see if you can get someone to bite for $750 or so. Other than that I'd just hold on to it and wait it out a bit.
I tell ya, I'll buy the box from you though!
