As you seem to be from the U.S., Ceretropic would be your best bet to get all 3 variants of the Epithalon peptide with high quality (they also have a sample pack offer for all 3 versions: https://www.ceretropic.com/epitalon-sample-pack).

To be honest, you should not bother with the normal Epithalon version and go directly for either the acetylated version or the amidate (NA-Epithalon or NA-Epithalon Amidate respectively). They both have much better bioavailability and potency of regenerative effects.

Epithalon is best administered either with subcutaneous injection, intravenous injection or as nasal spray (because the route from the olfactory nerve endings to the brain is also a good carrier gateway for the peptide).

Epithalon is a synthetic (and improved) analogue to the natural pineal gland peptide bioregulator "Epithalamine", so logically there are no natural sources.

If you are also on Facebook, check out the international Epithalon FB group for some independent discussion/info: https://www.facebook.com/groups/1628047714111352/