I must agree with my fellow realtors, giving an exact answer to your question is impossible without knowing many other factors such as what are the comps that have been sold in the area etc. I would find a good realtor who can assist you. I do know a great realtor in that area and would love to share his info with you if you like. You may contact me via my email firstname.lastname@example.org or to my cell 917 294-0356.
This is a buyers market you can offer less and see what the response from the developer. They may be in trouble and willing to negotiate.
good luck - Karen Abramson