Here you go!
I ordered them from Truckperformance.com because I couldn't find any locally in any brand. Well, Schucks carried 55W bulbs, but they were out of stock and I think they were $12 a piece anyway. So, I found the basic 55W PIAA H3 at Truckperformance for $3.91 each and ordered 4 of them. Since the factory fogs aren't sealed, it doesn't make sense to put expensive bulbs in them. As it turns out, the basic PIAA puts out a very bright light anyway. So far they seem like a bargain.
A couple things to note:
The PIAA H3's have a flat plug on the wire instead of a round plug like the 35W bulbs have. So, you have to cut the round recepticle off of the stock wire inside the fog light housing and crimp on a flat female spade type recepticle. Easy job! Sorry, I didn't take pictures of that, but if you have a couple flat recepticles and some wire crimpers you're in business. Nissan probably made theirs round so you'd have to get the cheesy 35W bulbs from the dealer for some insane price.
Since you would be running them for extended periods of time, you should get the glass lenses from xterraparts or such to replace the plastic lenses. Otherwise, the extra heat from the 55W bulb will likely haze the plastic or possibly even melt it. I didn't do the glass lenses because the backup lights are never on long enough to create any significant heat.
The shipping on the PIAA bulbs was a lot ($9 for all four), so you may as well buy extras and get them ahead of time, IMO. Even at $9, the price is the same or better than what you will find locally.
Hope that helps!
H3 Lighting at Truck Performance Centers