If you haven't tried lubricating the pulley bearings, try that first -- I can't imagine your pulley bearings going bad at 100k. If they are going bad, I seriously doubt you could purchase just the bearings to press into the old pulley. Would be too much trouble anyhow -- I'd just purchase new pulleys if that's the case.
Also, take a sideways look at your serp belt as the engine is running. Make sure there are no wobbles in the belt and that it is spinning perfectly smooth. You may have a pulley that is not on correctly, or just not pushed in all the way.
Which front seals are you replacing? If you're replacing them all for preventive purposes, follow the job# for removing/replacing the front timing cover ... if you have the CD's for the 124. That should cover just about all of 'em.