You might take a look at the Free Form Hella Ralle 4000 Halogen lamps. They are shown at this link for $125.99 each.
You would need a little over 4" of clearance from the bolt hole to the back of the light to mount them on the bumper. Not sure if that's possible with a stock bumper.
Another option would be the Hella 700FF at $77.39 for the pair.
The 700's are a thinner light and would mount on the bumper fine. They come stock with a 55W bulb which could be upgraded to a 100W for better output with no problem.
As a general rule of thumb the larger the reflector the more light it will collect and the more light you will have on the road. The 4000's are a 8.75" light and the 700's are a 7.5" light. The 500's which are the next step smaller are around 6.5". I just installed a set of the 500 fog lights. They are a good value for a fog light that fits in the light hole of an Aluminess bumper. If you have the room I would suggest going bigger than the 500's if you want bright lights.
Check out the Rallylights.com website for other ideas. I am a happy customer of theirs. If you have questions about the lights call their 800 number and talk to Will. He's very knowledgable when it comes to lights. He helped me quite a bit on my recent purchase.