There are several carriage home communities in Exton. It is difficult to provide a price range without having a better idea of which community you are interested in, along with any options that you may be considering. Furthermore, incentive packages tend to skew the data so it's very important that the data you seek accounts for them. Finally, with proper representation, further negotiations can always yield a better value proposition.
Feel free to contact me privately through this forum if you are not already working with a Realtor.