It's a job you can do by yourself. Tough part is getting the bottom bearing off the steering stem because it's pressed on. I took my bottom clamp and step to a machine shop and they pressed the old bearing off and the new bearing on, and I think they charged me $5.
The other tough part is getting the races out of the frame tube. Take an old flat head screw driver and slightly bend the tip. This will allow you to get the screw driver on the edge of the steering stem bearings and bang them out.
Get a brass punch to tap the new races back in, so you don't nick up the frame tube and races. It takes patience, but it's fairly simple to do.
It goes without saying, but be sure to pack the new bearings with grease !!