A 26-year-old man who was defrauded of his £800 iMac said that he was “over the moon” when officers returned the cash.
Sussex Police said that he wanted to warn others who were selling goods online not to get caught out in the same way.
He wants people to know that if they are paid through their PayPal account they shouldn’t allow the seller to collect in person as they will not be protected by eBay or PayPal.
Chris Edkins, of Brighton, believed that money had been placed in an online PayPal account by the buyer of his iMac computer on 18 May.
He then arranged for the man to collect the iMac from his home address.
He was told that the buyer’s son “Joshua”, who just happened to be in Brighton the next day, would pick it up.
However, when the man arrived Mr Edkins was suspicious and memorised his car registration.
PC Richard Valder Davis said: “Mr Edkins handed over his iMac but after checking his online account again two weeks later he found out that the credit has been returned and he no longer had the £800 in his account or his iMac.
“Thanks to the details he gave, our investigation led to a man being arrested in South London.
“He denied being involved in the fraud but within a day of his release he provided the victim with £800 cash.”
Mr Edkins said: “I can’t thank the police enough for everything they’ve done. I really appreciate it.
“I was in utter shock when they handed me £800. I’m over the moon.”
PC Valder Davis warned: “I would urge people to be careful before they hand over their goods.
“They should ensure they have been paid by checking with their bank.”