Yeah, that's the trade-off - you get it cheaper, but you're checking in to the roach motel.
I've tried to buy my books DRM free where I can, and by and large I don't by books on Kindle for that reason.
This was the first time however, I've seen such a difference in the pricing, as pretty much every other provider seems to make a note about the book being offered DRM free as a request from the publisher.
Actually this is the link the author uses on her own site, so I figure this would probably be better than the good reads one I added above:
Anyway, looking forward to the next reading group session!