Buying campaigns has always been a questionable endeavor for me. Realistically, how many times am I going to use that same campaign? Why would I use the same campaign again and again? If I wanted a game where the content never changes, I'd buy an MMO like WoW.
So, should you produce this, my personal opinion is that while honestly, I probably wouldn't buy it at all, I would be most inclined to buy it as a "Book 1: story" and "book 2: encounters" setup.
That way, if I want to run heavily modified encounters or custom-made encounters for the game, I could use the story to make sure they fit. Conversely, if I were to run a different game, I could use the "big-book-o-encounters" to base other encounters in other games off of.
However, I would be unlikely to purchase them as a set. I would probably end up buying one book and then a year down the road buy the other(if I did at all).