The cost of an urban gardening project will depend on the size of your project. If you choose to volunteer or used shared materials, of course, the cost is free! Garden plots range from $10 to $40 per year to be a garden member (a rule that is self-imposed by each community gardens’ guidelines. Recreation and Park Department does not charge any additional fees on top of what each garden asks of its members).
As far as seeds and other gardening materials go, that is all dependent on what you want to grow and how much! We’d suggest finding out more about where you want to garden in order to get a better idea of how much it might cost.