But Christian said the Facebook taunt made things worse, and initially he was scared the thieves would be able to find his home.
"It's that feeling you get when you think you're going mad and then the stress kicks in."
He said the costumes were irreplaceable and were needed for a dance performance at the end of next month.
"I don't think the guys that stole them will use them, unless anyone sees them dressed up in troll suits in Otara."
Though Christian also lost school work on his computer, he said all he really cared about getting back was the costumes.
Christian's property, along with the car on loan from a mechanic, was stolen from the Victoria St carpark between about 1pm and 5pm on Saturday, while he was at a performance of The Sound of Music with his mum and his three sisters.
Mrs Swan had planned to drop Christian's gear at a friend's place after the show before taking the children to dinner as a birthday celebration for one of his sisters.
Christian's dad Matt Swan said he was "wild to say the least" and the "low-life" thieves' taunts to his son made the crime even more offensive.
"The little shits sent my son a message to his Facebook account gloating about what they had done ... what low-lifes."
After committing the crime what kind of low-life then messages my son on Facebook gloating over the theft of his belongings?
"I was in total disbelief - like he needed salt rubbed in the wound?
"I felt sick. What values have these culprits had instilled in them as youngsters? Clearly not the values that we instil in our children."
A police spokeswoman said the car was found in Otara town centre on Monday.
There had been some damage to the vehicle, which Mrs Swan said included a blown gasket and a kicked-in door.
A police inquiry into who was responsible for the theft was ongoing, the spokeswoman said.
Mrs Swan said that although the car was recovered, the contents were gone, and she did not know if insurance would cover the stolen items.
An Auckland Transport spokesman said CCTV images from the carpark would be released only at the request of police as part of their investigation.