The following is taken from Ebay.
In general, take extra care when you are buying tickets, as the law prohibits the re-sale of some kinds of tickets unless you are an authorised seller. Check the individual policies below before bidding or buying if you are at all unsure:
Aeroplane Tickets
Train Tickets
Football Tickets
Contracts and Tickets
Check the seller’s feedback – don’t just look at the overall score, but also read the comments left by people who have already bought from them. This is the best way to get an idea of how trustworthy a seller will be.
Remember: If the price seems too good to be true, it probably is. All eBay sellers are required to include the correct face value (excluding booking fees) of the ticket when they list it for sale. Make sure the face value the seller has displayed is what you would expect.
Check the P&P BEFORE you bid or buy as unscrupulous sellers can inflate these charges as a way of making more money.
Pay with PayPal. This means you have a traceable payment, and you may also be covered by PayPal’s Free Buyer Protection.
Do not pay with an Instant Money Transfer, such as Western Union or Moneygram, as this payment method is not allowed on eBay.co.uk. Find out why.
If possible, confirm with the seller that you will be able to receive the tickets in time for the event. As a minimum, make sure the delivery options offered in the listing mean you will get them before you have to leave for the event.
If you arrange to pick the tickets up in person, use your common sense and take the usual safety precautions: make sure you meet in a public place, take a friend with you, and do not agree to carry or hand over large amounts of cash.