While the concept of supporting the Jewish store is nice, it doesnt factor in the major cost difference.
I can get chicken at ShopRite for $1.99/lb (rarely, but its available otherwise its $2.29-2.49/lb), whereas the same chicken is $2.99/lb at the kosher store. So if you are buying 1 package, fine, but if you are feeding your family? Over a month that makes a large difference.
If I shop at the Jewish-owned store purely because he is Jewish, can I use maaser money on the difference? After all, me shopping there is PURELY for charity reasons.
I need to first worry about my family. We live on a tight(ish) budget, and increasing our food budget even more is just not affordable. I don’t buy non essentials anyway, and for essentials I shop around for the best price.