It's worth trying to work out. People love exchanging money for goods and services. The more you can do for them aside from actually reading the book for them, the better. When other people take care of things, one can relax and enjoy oneself.

Even if you can only do it for 50% of members because of whatever logistical problem, it's worth it. Although it seems it'd be simple enough to email publishers and offer to buy X number of copies of an ebook in the context of a book club.