Booksmarts prices seem to be cheaper.....prices listed for 40 page books, are close to Picaboos price for a 20 page book. You can make it as many pages as you'd like....and of course the selection of page layouts hold from one to 20 photos.
The book I just ordered was a 40 page book, which came to 69 bucks.....but they always have 'specials'....as they did when I ordered this one (which was 50% off) which brough the total to $44 including shipping and handling. I can check later how many photos actually went into it, but it's safe to say you could easily get anywhere up to a couple hundred photos in a book....depending on how you want to set it up.
Picaboo has a broader selection of page layouts and backgrounds than Booksmart.
One feature of Booksmart (which made me think of you Michel), is that once you have put together a book, you can put it out there in their 'Book Store' section, for sale.
I'm working toward having ALL my photos in books.