Except for books of exceptional interest to me I buy un-DRMed ebooks or DRMed ones that I can convert. (Note - exceptional interest sometimes includes pBooks.) However I find that I have a strong tendency to buy new books of casual interest as un-DRMed rather than another book of equal price & (otherwise) value that is DRMed. Therefore the authors/publishers that DRM their ebooks are losing sells
(at least to me).