That depends. Is it over 9,000?
In all seriousness though, I'd look at some of the vanilla Skyrim meshes. They are a pretty good match for today's PC capabilities, but the poly count can always go much higher. It just depends on how big of an audience you want. More detailed meshes would be a big hit for those with powerful desktop computers, but you might exclude some of those with lower end setups.
That said, if you're only using a mesh once or twice, you can go pretty high on the poly count. (Giant statues are an example, so long as it doesn't go into the LOD. Ouch... Might want a lower poly version for anything going into LOD...)