Samhain also sells
directly from their website (and they give 30% off new release books) in what looks like DRM-free MultiFormat. They seem to be reasonably fair to their authors, though I'm not really in a position to know.
But I'm surprised that your Sony won't take the Samhain books, because they're sold as plain non-DRM ePubs over at B&N (at least, all the Samhain freebies I've ever gotten there have opened in just about any random ePub reader, Lucidor & that other Firefox ePub extension included without having to strip), rather than B&N-DRM ePub/PDBs.
ETA: Quickie check of my copy downloaded directly from the B&N website and dragged over to Lucidor works fine and opens with all text readable. Lucidor normally gives a snarky error message when it encounters DRM of any type.