I'm in the planning stages of a 3D strategy game, and would like to know what sort of pricing would I be looking at for graphics?

There is not enough information to answer your question. It could be thousands or it could be nothing.

The price would be more effort

It depends on a number of factors. You could try purchasing premade models, in which case you should start shopping around for them. But if you plan to have them custom made then the price will depend entirely on the Modeller you higher. He could charge a flat rate, a percentage, both or nothing at all. If you'd like a better estimate, you could try asking in the Help Wanted Forum and inquire about some of the resident modellers individual prices to get a better idea.