I'm not sure what the market would be for per-download books, although it might well be something to try for at least the most perennially popular of titles. There's another way to generate an economic interest in PD e-texts though, and that's to continue to give them away, but promote the hell out of their use for coursepacks, esp. in areas like CanLit, history, and other social sciences. Universities, individual faculties, departments, professors, or TAs, might come to value the availability of these materials and the consequent reduction in the gelt they would owe to Excess Copyright. I hesitate posting this on an openly-archived list (Excess Copyright et al. ARE probably reading; hi, guys!), but I think this might be one very clever way of generating some real vested interests in a vigorous public domain in Canada.