On the other hand, if you want to learn to do your own work, hub bearings are a pretty good place to start. They are pretty simple, and the principles of bearing servicing and adjustment are the same for hubs, bottom bracket and headset, assuming your bb and headset are not the newer cartridge bearing type. Anyway, all you need are a good book like Zinn or Bicycling Magazine's Complete Guide to Bicycle Repair and Maintenance, and a couple of cone wrenches of appropriate size. Total investment less than $40, and the book you will use for everything. If you have to spend the money anyway...
__________________
If it ain't broke, mess with it anyway!