The phrase "normal supply source" can be used to refer to the typical or usual source from which a product or resource is obtained. However, there are several synonyms for this phrase that can be used interchangeably, including "regular supplier," "standard source," "common provider," "routine supplier," and "familiar source." Each of these phrases conveys the idea that the source in question is reliable, consistent, and commonly utilized. Ultimately, the choice of synonym will depend on the context in which it is used and the specific connotations that the speaker or writer wishes to convey.