In the grand scheme of things, eBay isn't bad. Check the sellers'
reputation on eBay by looking at their feedback. Here you can see
comments from previous buyers about their satisfaction with that
eBay requires all sellers to become verified by providing a credit
or debit card and bank account information. This helps ensure they
are at least 18 years old, ensures that they are traceable and also
increases confidence between buyers and sellers.
If you buy the item at auction they are legally bound to sell it
to you. If they refuse to send you the item (in the UK) it would
be considered fraud or obtaining money by deception. If you pay
electronically or by cheque your bank and credit card company will
have an audit of the transaction and, should they not send the item,
you have an easy audit trail for the police to follow and recover your