More often than not, there is no stock with the developers for the properties which are ready to move or closer to being ready, these properties are available in the "secondary market" or what some may refer as "resale market".
This basically means that someone who had booked earlier would not want to sell the property at the
current market price. Which would generally mean that the person who had booked earlier, would also be making profit on the property. Although the better way to
acquire your property is to be the first and the original allottee, there are number of reasons for that which you may explore on this LINK.