The incident took place between midnight on Wednesday 20 September and 4.30pm on Sunday 26 November 2017.
The Millennium Falcon Star Wars set was removed from its packaging which was then filled with other items to conceal that the Lego was missing.
PC Phil Johnson said: “The victim is extremely upset about this incident. It is a very rare Star Wars Lego product that contains 7,500 pieces.
“It is likely he will never get the opportunity to purchase one again. It is not about the monetary value of the loss, but the fact that this was a collector’s edition.
“Anyone with information should contact police via email@example.com or by calling 101 quoting crime reference number CR/103058/17.”
Information can also be passed anonymously through Crimestoppers on 0800 555 111 or www.crimestoppers-uk.org.