The bearings are relatively inexpensive skateboard bearings but they seem more than adequate for the task. The bearing axles are ordinary cap screws. You could certainly spend more money on both items if you wanted to make an upgrade. I think it would be better though to first upgrade to ground flat stock for the rails. Then probably 3:1 reduction on the x and y steppers to get better resolution and then add in the higher quality bearings and axles. It all depends on what you want to do with the machine.