Viking Forge has Palmyran Cats and light horse. No foot, although they have Sassanid foot archers and Roman Auxiliary that could do.
Poses are more static than is currently popular.
OG15s have Cats, light horse, and foot archers. A bit larger and it was a tight squeeze getting four Cats on a 40x30. Well animated though.
The Cats from the Battle Honors Sassanid range are generic enough to be used for Palmyrans as well. A bit more expensive. Haven't painted and based mine yet.
Donnington has nice figures, haven't painted them up yet and they are UK, so shipping time to consider. But they do have a Zenobia and Boudicca.
Same with Essex.
Here are some photos of my Palmyrans for an idea (OG15s, VF, old Essex, and Minifigs) -
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OG on the left VF or the right.
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OG left, VF center and right.
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Minifigs left, Old Essex left of center, OG right.
OG Romans for the DBA 'a' list -
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Colors are a bit washed out, but size and animation can be seen.
P.S. I think Stever that photobucket takes that title…