I have been offered the opportunity to buy multiple like new copies very cheaply of The Moral Center: How We Can Reclaim Our Country from Die-Hard Extremists, Rogue Corporations,Hollywood Hacks and Pretend Patriots by David Callahan (published 2006). At first I was thrilled cause I thought people would snap them up here but then I wondered, would I just end with a whole bunch extra books? And while I could sell them on ebay or amazon.com, I am not sure I want to mess with that. I would rather get credits to use here:)

How could I make a reasonable guess on how many I should buy to trade here? What would you do?

Well, I just looked up the title and it looks like there are copies already available for order.

I would enter the ISBN and see if it's already available. If not, see how many are wishing for it and then I'd judge based on that. If it's available already, I'd add it to my RL. If there are only 1 or 2 copies, I'd guess you could get a couple and they'd be ordered fairly quickly.

If they're in like-new condition, you could post to the Bazaar that you have giftable copies of the book available. That might move them quickly.