The Kwanzaa principle of Ujamaa deals with the concept of Cooperative Economics. It encourages support of local cultural enterprise, which in turn strengthens community. There is a blog that goes into detail about this fourth principle, so I won't go into more detail here; feel free to read it for yourself.
Some suggest, for those of African descent, that Ujamaa means we should shop in stores owned by those of African descent. That such commerce is Ujamaa. While I would not disagree, I would suggest a slightly more expansive understanding.
If this principle is based on African communal living in which resources are shared both within the family and within the village, we must consider supporting local business because our villages, or neighborhoods as it were, are best supported through local enterprise.
For example, my husband and I have seen the death of small town life at the hands of big box enterprise; "Buy-N-Large" type stores (if you don't recognize the reference, read here...) sell many products, often at cheaper prices, than the "mom and pop" shops right in the downtown. Folks are willing to travel to get to the BnL store, taking the money out of the local village, causing the mom and pop shops to close. It is a viciously sad cycle.
In order to live out Ujamaa in many of today's modern villages, those of African descent should support the small merchants in their local community...if there are black-owned stores, shop there. The only black-owned business close to us happens to be a barber shop; no one in our house goes to a barber. However, our village includes Latino/a owners, owners of various Asian descents, and owners of Arabic descent. We shop in them often. We do it not just to financially support our village, but to build the village--by relating to our neighbors in this way, we build community.
We build lasting friendships.
We build family.
Ujamaa is bigger than commerce. Understand that and you got it.