It is depend of the hardware and the type of your game end other values(like how many characters are visible at once)-if you aim for actual machines than go from 5000-10000tris (iam using for a FPS).

Actual machines have a lot power for polys-its more the shaders that make actually the "brake". On older machines i would not use more than 5000 tris.

From the better machines iam talking about fastest GF6 class to actual once.