For those wondering about the library, or just the real estate aspect in general, here is a short run down from my experience:
Priced on lots fluctuate a bit in game, mainly they get more expensive then would be expected before in say sunset valley. However, now you can buy much more then just businesses, now you can buy community lots. Basically, when you own a community lot you can build on it, as well as buy mode for it, all from the little button when you click the lot and press "Real Estate...". There are only three levels, though, for the properties to be "upgraded" to and many I bought were already at level 2. So, for example, I needed 2 grills, a picnic table, and a little value added to the town park and it was maxed, bringing in more cash each monday. So far, the rendezvous spot is worth the most I've seen and has been the hardest to upgrade as well.
How this relates to the library, the library in the beginning of the game is a basic, non-upgraded lot, when I bought the library, when I added a shelf with skill books in the new buy mode as owner it gave me enough value to upgrade the lot with the other items I needed. This may be why it is such a crappy library to start, and it certainly is why the rendezvous place mysteriously has two empty floors (you'll need them!). Planning to buy the consignment shop on my next sim and see if that does anything to how it works, but buying things like the grocery, spa, or even the stylist shop didn't change the pricing on those places, it only affects the restaurants which when you become partner you eat there for free. However, I think that's been the case for awhile.