Unfortunately most foundations, particularly the ones that are larger in scale, do require the organizations that they fund to have 503(c)(3) status. There are a couple of ways around this. One is to explore fiscal sponsorship. If there are organizations with which your space partners that do have 501(c)(3) status, there is a relatively simple process by which you can gain fiscal sponsorship, and therefore be able to apply for grants using their 501(c)(3) status (as an umbrella). There is a useful section on the Grant Space section of The Foundation Center's website on how to go about getting fiscal sponsorship http://grantspace.org/Tools/Knowledge-Base/Funding-Research/Definitions-and-Clarification/Fiscal-sponsorship.
Foundations or organizations which are more likely to offer grants to groups that do not have 501(c)(3) status tend to be smaller and local. It couldn't hurt to reach out to local arts councils and/or foundations that are specific to your city or town. Since you have a local focus, they may be willing to overlook the lack of non-profit status, or they may have grants where this is not a requirement.
Although they mostly focus on grants for 501(c)(3) organizations, it worth looking at the list of cooperating collections with The Foundation Center http://foundationcenter.org/collections/ to see if there is one in your area. These centers are often hosted at public libraries and provide access to countless resources (both print and electronic) for finding foundations and grants that fit the specific needs of your organization.
