At what point is your collecting hobby considered a business

[polishman]

I know this is question probably better suited for an accountant but I'm curious how many of you that sell on ebay, trading forums and card shows actually are registered with the IRS and state as a business. I owned a hobby shop for a few years and sold it a couple years ago. I have a revolving collection that everything is always for sale and almost all money goes back into buying better cards or upgrading ones I've sold. I sell quite a bit on ebay, have done some card shows, but almost never use my profits for anything other than buying more cards. I consider it just a hobby, but would like to hear what other members think about the card hobby/business and when do you think it's time to start going legit as a real business.