Solunars by Aldebaran Sidereal Academy

I'm already familiar with Valens, Manilius, and Ptolemy. But there must be more material. I would like to be good enough in Hellenic astrology to make Hellenic natal charts and so on. Is there any decent description of Hellenic zodiac signs out there, by the way?

Hellenic zodiacal signs are the same as you know. Manlius, Valens, and Firmicus are the standards. (Oh yeah, you didn't mention Firmicus Maternus. He's probably most representative of the maturity of the period.)

Check out Project Hindsight : http://www.projecthindsight.com/article ... istic.html
They have new translations of Valens, Ptolemy, Firmicus and somebody or other. Look on their "Products" page.