A client wants to create a site that sells little items like coffee mugs. They're thinking about using CafePress.com or a similar service to make the process most simple for them.

They don't expect much revenue from the site, but they'd be happy if a couple of them sold a month.

My question is - does this person have to register their own company if they're going to sell items online? They'll have to pay taxes on these items, right?

And what if they're selling through a third-party service like CafePress? Do they still have to register a business and pay taxes on sold items?

Thanks for any help.