Done it a couple of times...
if I remember right, the bearings run about $12 each and the seals $5. If you've still got the auto hubs...pay close attention do your haynes or chilton manual on how to disassemble the hubs. If you have already gone to warn, which I'm guessing you haven't beings that your asking about doing the bearings...it would be a lot easier. Once you get down to the bearing, you can just pull the rotor off. Sometimes it takes a little muscle. You'll be able to just pull the front bearing out, then tap out rear one and seal. This is also a good time to have your rotors checked. When your ready to put back together, put the new races in place, then pack the bearings. The easiest way is just to fill the palm of your hand with a larg amount of bearing greese, the press the side of the bearing down into your palm, forcing the greese through. Place it in the race, then put the seal in. The best way I've found is to lay it as flat as I can, then use a 2x4 piece of would to keep even force on it while putting it in place. Put the rotor back on and insert the front bearing already greesed as well. Reassemble the hub paying special attention to torque specifications. I mentioned earlier that there was a good time to check your rotors....when you do your bearings its a great time just to do a complete brake job. Beings that your going to have it all apart anyway. Good Luck....hope this helped.