I had a yomega with a cracked inner race, and i ordered it directly from yomega :o But I had about 3 plastic grind machines and i wore a bearing out on 1 of them, the other the bearing is about to go, but they only last about as long as the yoyo does for me before they fail, but if it were metal it would be more dissapointing. I outgrew the plastic grind machines anyway.
you can always order yoyos from china with cc size c bearings and switch em for the yyf stock bearing and sell them to someone starting out in yoyo, or just order a full ceramic like i did in my yomega dash.
I would recommend a full ceramic in any yoyo that is on the heavy side