I have received a message from eBay because I have sold over 30 items in the last year.
These are my personal items and the total value is only £500 but I have to give my NI number as I have sold over 30 items, although I can sell personal items to the value of £1000 without any tax obligation.
I thought I would give a heads up as if you sell low value items you will soon pass the 30 limit.