The introduction of £1,000 allowances for trading and property income was designed to be beneficial to those who top up their income from casual or self employment income including online selling.  

Care should be taken however as all trading and casual income is combined when looking at these allowances.  These allowances are unlikely to be beneficial for individuals where they already have an established self employment and top up this income with a completely separate small business.  

This is another occasion where there are traps in HMRC's attempt to simplify tax - beware!