If you’ve found little ball bearings on your floor because your casters have worn out on the chair you sit in everyday, then check out this source, and choose a maintenance free wheel that can support more weight.
The retailer that may provide the parts you need will only be giving you the same thing… so expect the same life span. Caster City has just about every type of caster made. They are very easy to replace… simply turn the chair over and grasp the wheel firmly and pull hard. If the caster has a screw on post, then you will need a wrench. A set of these are under $30 and will bring your desk chair back to life.