Reply To: Buying at a Jewish shop vs. a Non-Jewish shop

From Business Halacha by Rabbi Meir Orlian:

Question: Is there halachic basis to give priority to patronizing Jewish businesses?

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.

[Edited to correct attribution. Thank you WolfishMusings.]