Rec Needed: Sunscreen

Hi all, I am an undergraduate student majoring in exercise science. I am going to be testing different sunscreens under a variety of conditions (mainly water and sweat) to validate their advertised protection durations. For testing, I am using two high level product groups: natural and artifical (dare I say unnatural?).

I am having no issues finding information on sunscreens (that are produced by large companies). I need assistance finding "mom and pop" companies that produce natural sunscreen products.

Does anyone know of such a resource or website?