Personally, I won't be buying any ebooks from anyone until prices are substantially lower than printed copies - like $1.99-4.99 cheap. I have a problem with the whole concept. When I buy a book, I can read it without any tools. This is not the case for other media - I have always needed a VCR for VHS tapes, a DVD player for DVDs, a tape deck for cassettes, a CD player for CDs, etc. There was always a lock-in for audio and video media, and buying content on them you are pretty much garaunteed that someday you would not be able to use it.
Books, though, are a permanent commodity. You can buy 1000 year old books (if you have the means) and still read them, and if properly maintained you will be able to read them in 1000 years from now. An ebook, though, is only good as long as I have a reader. I'm not convinced that I will always have access to a device that can read an Apple (or Amazon, or B&N) DRM restricted epub file. As such, I don't think they have a worth even nearly equivalent to their printed editions, which is what the publishers seem to think.
Additionally, ebooks share the same issues as other digital media in terms of vendor lock in and loss of resale or loaning rights. This also reduces their value to the customer and should be accounted for in price. iTunes did this with music - albums were/are often $12-15 but digital downloads are $10.
So, until they price their product as nothing more than a long term rental, I'm not buying. I'd happily pay $2-3 for ebooks which are >1 year old (typical paperback age) and $4-5 for newer titles, but that's about the limit for me. I am happy to download public domain works through iBooks, and I am willing to go find other sources for books which I already own in print just for the simple convenience of reading on my iPad until then.