Just download the SAMPLES, people!! That way, ya only buy the book when you have already started reading it. It spreads out the cost quite a bit. That plus, yeah, all the free books.
However, if it is a best-seller, at $9.99, and you know you will want to read it -- sometimes it IS best to buy it now. Prices do go back up after a new book isn't so new, but isn't yet available in paperback or otherwise glutting the market.