Negotiating with builder to leave walk out basement unfinished

[Rich Gabrio]

I am currently looking at new construction SFR as an investment north of Seattle area, in a development with one remaining home where framing has just been completed, electrical work to begin soon. This home is the last home in this plat. These homes range from 3000sf to 3600sf and each have finished walkout daylight basements and these sold homes have recently and consistently sold at $220/sf. Typically this builder prefers not to list the homes until carpet is in. Conversely, most homes in this specific area/town are selling at closer to $300/SF. I assume that the price $/per sf is lower on these homes, due to the daylight basement, as ramblers built by the same builder across the street are currently at the $300/sf range.

   1.) Is my assumption regarding price difference due to basement correct?

  2.) My agent and I have been discussing a scenario where we approach or submit an unsolicited offer to the builder for a lower price with the basement unfinished (Ie; insulation installed phase).  This would potentially bring the price point into my acceptable range.  I am wondering if any builders can help with some insight as to how best to estimate a fair price for this type of scenario?  Would builders generally be open to this type of scenario?  I am hopeful that the builder might be open to something more flexible, as it's the last house, and he does not have to worry about setting a new precedence in this plat. How best would you advise to handle this discussion?

My initial inclination is to calculate a price using the $220/sf for the top two floors, and a discounted price /sf for the unfinished basement. I am not concerned about the cost to finish the basement after the fact. My initial research seems to indicate that the price /sf could be as low as $35/sf and as high as $70/sf.  I suspect the markup would not be very high, given the roughed-in status, but I want to present something that is fair, but also not leave $ on the table.

Thanks in advance for any guidance.