Haha... this thread makes me feel so old. I'm in the same generation as lots of people who like real books because of the "feel" or whatever. The world is moving towards digital, and no amount of comfort or familiarity is going to change that. Newspapers are dying. Magazines are dying. Books will die. They'll have a market for decades to come, simply because those of us who prefer reading books will still be around, but once the digital generation starts to have widespread access to ebooks, you know sales of those archaic paper monstrosities are going to drop as well. It would benefit authors and publishers alike to take advantage of this, rather than fighting it.
Now, for monthly series released on ebooks (any series, since I'm fairly certain Katherine and Michael were not asking about Animorphs specifically)... I'd buy them, but I think at least a small amount of advertising would be necessary. I can't buy something if I don't know it exists, and I won't if I'm not intrigued. I probably wouldn't pay more than a couple of dollars apiece for a series of short books similar to Animorphs or whatever... maybe $3? Monthly series hold the advantage, however, of being able to sell subscriptions- you could even keep the same price per book and just throw in extras for monthly subscribers. It might actually be advantageous to stretch the wait time between volumes- it almost seems like a bi-monthly series would feel more substantial. Of course, then you risk your audience losing interest or growing out of the series... Haha, okay, forget I said anything. For one-off novels in ebook form... I probably wouldn't be willing to pay more than like... $7? Give or take? Depending on how interested I was, of course. Set the prices too high and you risk losing more customers to piracy. And I know I still much prefer reading on paper, so until simulated paper technology becomes more widespread, I think the prices for ebooks have to be kept nice and low.
I totally agree with delta that there should be some sort of trial period... or (in a cruel but probably very effective plot) maybe the first few chapters could be made available for free. Something similar to the way you can cruise a few pages of books in the bookstore before purchasing. For a monthly series... I'm not sure I'd release it alongside paperbacks, honestly. Exclusively ebook series make much more sense than paperback monthly series in today's world. Shorter series and standalone novels need to start being released in electronic incarnations alongside their physical versions in order to propagate the ebook trend.