The UK Co-operative group is probably an example of one of the most successful and long lived consumer co-operative, with 60k+ employees and has been operating sine 1844. https://en.wikipedia.org/wiki/The_Co-operative_Group PS: I have absolutely no connection with the UK Co-op, just thought they make an interesting example.
Consumer coops are valuable and useful as steps in a process, initial steps often that teach those who build and use such coops about the multi-level economic, cultural, personal, and other benefits of such community efforts. My hope has always been that they can and will serve as steps toward recognizing (1) all the other areas of life where community, collectivity, and solidarity have been systematically constricted and distorted by capitalism especially, and (2) what can be done within capitalism to move beyond it to a system that much more allows, fosters, encourages and rewards community, collectivity and solidarity.
As an economist who has come to appreciate the centrality of the workplace alongside the household and other crucial social sites, I have devoted my efforts to analyzing and promoting the cooperative organization of production itself as a crucially necessary alternative to and movement beyond the employer-employee dichotomy emblematic of capitalism. My goal would be to make consumer and worker coops supporters of one another's existence and growth.