From the research I've done you have a limit up to £6K a year on selling personal items (as shown above), as this is the limit for inheritance income you can receive before getting taxed.
If you're a buying in new stock and re-selling it then it's a limit of £1K per year before you get taxed.
That's the way I've read it so I'm thinking things should be fine but we'll have to wait and see if the tax man comes calling. I have also heard that next year the personal tax limit will be halved to £3K, so we'll have to wait and see about that.
Ian