Definately stick with factory AISIN hubs. The swap is easy. As mentioned, just find ANY 1986 to 1995 pickup or 4Runner (do not get anything 1985 or older because they are different). I have done this swap a few times. You can often find hubs for sale on Ebay or on these boards. Typical pricing for a complete set of hubs, springs, washers, nuts, etc... is about $50-$100.

I've converted a few 1990-1995 4Runners from ADD hubs to the manual hubs, and it's actually helped fuel economy by about 1-2MPG as well. Your year 4Runner is lighter though, and probably won't have as much of an effect on MPG, but I would still expect to see a slight improvement. With fuel costs the way they are (we went over $3.00 today), the hubs will pay for themselves in no time.

I also recommend staying away from the Warn hubs. While I've never used them, I've heard nothing but bad things about them. If I recall correctly, they stick our real far and are prone to getting whacked, and they use some plastic parts....