Swap Bottom Bracket bearings or replace entire bottom bracket? I've recently acquired a 2007 Specialized Allez. As I was dismantling the bike for service, I discovered that the bottom bracket bearings are in rough shape. They aren't smooth at all. I took apart the bottom bracket cartridge and I've pulled out the sealed bearings.

Is it typical to replace bottom bracket bearings? Or do people usually just replace the entire bottom bracket cartridge all together? Looking on sites like Performance Bike, they don't seem to carry bearings at all.

Also, if I decided to replace just the bearings, do I simply need to find a good quality set of bearings that are the same size as mine (in this case 15mm x 32mm x 9mm)?
Without specially fitted tools, it is very difficult to install new bearings in a cartridge bottom bracket. Usually, the act of pressing the on to the BB spindle puts enough side load on the bearing to damage the new bearings. 

If you want to give it a try, yes, you can just go to your local bearing house and match the bearings by the numbers printed on the rubber seals. 

The normal procedure is to replace the cartridge, but the bearings are cheap, so it's worth a try, even if it's just to learn that it doesn't work out.