Can Communities Hire A Private Security Company in Place of City Police?

Many community activists are calling for some kind of boycott during the holiday season in order to protest racial injustice. Some point to the successful Montgomery Bus Boycott as an example of how withdrawal of financial support can force necessary social change. But others say that the wrong message was sent with the efforts to desegregate buses in Montgomery: What should have happened is that African Americans should have used the money they saved to buy their own bus company. With that thought in mind, what would happened if communities hired their own private security company? Would that eliminate conflicts with racially biased city police officials? How much money would participating citizens have to contribute? Are there any existing companies that people trust to police their communities instead of the city police? Are enough communities organized into or neighborhood associations that are able to legally hire a security company to patrol their streets?