Ford online dealer price is $176.62. Includes ABS sensor and new bolts
Rock Auto has Timken SP470200 for $143.79 includes ABS sensor. A member on another thread posted this about the Timken ones
"OK, finally got the bearings and brakes done. Got Timkens with the ABS sensor (from RockAuto this time, can't say enough good things about them). They actually came with new bolts (with the yellow threadlock) which I was not expecting. Came with bolts for the hub/bearing, as well as bolts for the caliper bracket."
Rock Auto also has National 515050 for $169.79 that also includes ABS Sensor and new bolts. That's $8 less than the Ford OE one.
Many of the chain discount auto parts stores sell imported sets that have varying quality and some have had issues. Ebay also has some a cheaper prices, but often of Chinese origin.
You can get Chinese made ones from here for $55.90 but doesn't say about new bolts (ABS sensor is mentioned on Feature Sheet).
http://www.primechoiceautoparts.com/p-5176-hub-bearing-hb615054-premium-hub-assembly.aspx
When I do mine I am going to buy the Ford ones as its not much cheaper than the National one from Rock Auto and those that have replaced theirs' with Ford units have usually had no problems.
SKF, National and Timken all make Hub bearing assemblies for the 2002-2005 Ford Explorer. I seem to recall that the National ones are US made bearings. Not sure about the others. You could go to those company websites and search their catalogs for further info.