The victim, who was yesterday named as Peter Battle, 56, was found at Whisker Cottage, in Full Sutton, near Stamford Bridge, last Thursday.
A post-mortem examination revealed he died of a head injury.
A man aged 26 from Norton, near Malton, was arrested in Malton at about 8pm on Monday and is being questioned at a police station in Hull.
Mr Battle, who worked from home, dealt mainly in silver and gold, particularly sovereigns, rings and cutlery, and it is thought a number of items are missing, along with a black and silver Advent laptop computer.
He was well known in auction houses across Yorkshire and inquiries are being made within the trade. He also dealt frequently on the internet auction site eBay.
There was no sign of a break-in at the detached property and police are appealing for help in identifying anyone who had visited the address since Christmas. It is thought Mr Battle, who had been dead for some time, had been visited on a number of occasions prior to his death.
Det Chief Insp Alistair McFarlane said: “We are keeping an open mind as to what may have happened but the fact that he was dealing in antiques is an important line of inquiry.
“We have reason to believe that some of those items from within Mr Battle’s property may have been stolen and would ask if anyone has recently been approached to buy similar items that they contact us with information.
“We also have information suggesting that a person or persons may have been visiting the property in the weeks preceding the discovery of Mr Battle’s body.
“Sadly, we think that Mr Battle may have died quite some time prior to our discovering the scene of the murder, and we are keen to have information about any movements at the property from around the end of December 2012 until that time.”