Where can I find/Buy Tablet pen tips or nibs?

is there no web page link in perhaps in the software help files that come with the tablet. I can't find any info on your device but then you are not sure of what it is either. The best advise I can give is to perhaps ask the place you bought it from if they do replacement nibs or at least if they know where to get any from. If this is Comet then I doubt if you will get much help as they are unlikely to know the answer unless they actually stock the replacement nibs.