Connecting robot to wifi

Hi, I am looking to drive an arduino powered robot over wifi. Trouble is, the wifi shield does not offer the range i am looking for. Is it possible to connect an arduino uno to a router without buying the ethernet shield?

There are routers that can be hacked to include a serial port, but the ethernet shields are in the price range now that router hacking may not be worth the effort.

What sort of range are you after?

I was hoping to get about a hundred yards out of it, hopefully more, which is difficult on a budget, esp without the use of a directional antenna