Notwithstanding anti discrimination laws which may disallow a seller to only sell to other Jews exclusively. Suppose a Jewish fellow - living outside of Eretz Yisroel - lives on a block which is mostly Jewish and wants to sell his house. The highest offer he has received from a non Jew is more than the highest offer he has received from a Jew. Is there any basis in Halacha which compels him to sell it only to the Jew? Is there a difference depending on the price differential? (sources)
I am going to try and answer this question based on the array of sources that discuss SHOPPING in a Jewish owned shop, as opposed to a non Jewish shop. That discussion more or less goes as follows (based on מורי ורבי רב אריה ליבוויץ's ten minute halacha http://www.yutorah.org/lectures/lecture.cfm/815131/rabbi-aryeh-lebowitz/ten-minute-halacha-shopping-at-jewish-stores/)
Toras Kohanim derives from the verse, "When you sell something to your fellow or buy from the hand of your fellow" (Vayikra 25:14), that one should give commercial priority to his Jewish brethren. This halacha is not mentioned in Shulchan Aruch, but is cited by numerous responsa.The poskim debate whether the law applies if the non-Jew sells for cheaper. Rama (Responsa #10) cites this law to give priority to an edition of the Rambam printed by Maharam Padua over a competing, cheaper edition printed by a non-Jew. He understands from the Gemara (B.M. 71a; Pesachim 21b) that the law applies even when there is a price difference between the two and there will be a loss in buying from the Jew.On the other hand, some achronim argue that this law is only "proper advice" (Korban Ha'eda on Toras Kohanim). A number of others maintain that it applies only when there is no price differential (Maharsham in Mishpat Shalom C.M. 189). Maharam Shick (C.M. #31) also maintains that a businessman does not need to buy from a Jewish supplier who is more expensive, but should do so if it is only an issue of convenience.
Dayan Y.Y. Weiss zt"l leans towards differentiating between a small price difference, in which case you should patronize the Jewish store, and a large price difference, in which case you are not required to suffer a loss. [This is also the understanding of the Chofetz Chaim (Ahavas Chesed 5:6-7) in the opinion of the Rama.] However, Minchat Yitzchak concludes that if the small Jewish storeowner will be driven out of business and lose his livelihood, there is a greater need to support him, even if there is a significant price difference, if the customer can afford it. Thus, Rabbi Lebowitz concluded that according the Maharsham and other achronim mentioned above, there is no requirement to patronize the Jewish business if it more expensive. However, it is meritorious to follow this middle position and patronize the Jewish business if it costs only slightly more, and certainly if it is only an issue of convenience, as mentioned above, in the name of the Maharam Shick.
It would seem that we can try and draw across to selling a house. You probably are not obliged to lose money for selling to a Jew. You should probably be willing to suffer a small loss for the sake of selling to a Jew and helping him/her. IF this Jew is struggling to find a place to live, that should influence you to be willing to lose MORE money.