I'm with Sid; the only way we can possibly help you with polycounts is if you tell us the engine you're using, the visual style of your game, the target audience, the game camera setup, etc. It really depends on too many things to give you a definitive answer.
Quote: "does anyone know of a decent 3d RTS engine?"
I don't think you'll find a 3D RTS game engine--that's a bit too specific. You could get Torque; I think that there's an RTS starter kit. However most game engines do not target a specific genre. Off the top of my head I would suggest
DBP or
Blitz3D if you're not very experienced, but if you're a bit more experienced I would check out something like
NeoAxis (C# scripting) or
Unity (C# or JavaScript scripting. And of course you could always take
OGRE and combine it with a a decent collision system (like
MOC) and a decent sound library (like
OpenAL). There are many options for what you could use out there. Very few are specialized for RTSes so you can plan on studying AI a bit as well.
Sorry if this kind of discouraged you, I didn't mean for it to, but an RTS is a fairly big project and TBH at this point poly-counts should be the least of your worries as you can always go back and recreate your media once your done with the game.
i like orange