Is it legal? Private/non-profit to pay some volunteers a stipend that is not government funded but funded by agency itself?

If a private/non-profit wants to enhance opportunties for some of it's volunteers by providing a small stipend (simiiar to the AmeriCorp Program), and these funds do not come from any government funded source, but rather it's own resources, would this stipend be legal under the FLSA? If legal, would there be any specific criteria attached, such as age, ie. only students or seniors, or general population etc.?