I was told just recently 5-6k for a character and lot less for other models.
The reloaded docs state 'max. of 6k poly for characters' and '500 poly for general models'.
I know you want to keep models as low poly as possible but I think 500 poly is a bit low.
PC - Windows 7 64bit, Intel i5, 12Gb Ram, 1TB WD Black, Evga Gefore 760gtx 3GB
Laptop - Windows 7 32Bit, Intel Core 2 Quad Q9000, 4GB Ram, 500Gb WD, ATI Mobility Radeon HD 4850