The main worry Mr Slight had was not the cost of the minion but the pleasure kids would no longer have.
The display has been out since after Masterton's Christmas parade and the missing minion has one eye and flat hair.
Kim Olson, a Mega staff member, was annoyed at the disappearance as he made the minions for last year's Christmas float.
"You sort of think, 'Nah they wouldn't'," he said of people taking the display.
"It's not like there was a sign saying recycling collection."
Mr Olson spent about a week making each minion and said it was one of Mitre 10 Mega's best floats.
He said the minions were screwed to a pallet by their feet, which were also filled with concrete.
"They're actually more awkward [to carry] than they are heavy," he said.
Mr Olson suspected someone is laughing from afar.
"It will be sitting in someone's lounge with them saying this is really funny."
Compliments were often given about the creative display, which the store was thinking of moving above the children's play area indoors.
Mitre 10 Mega is appealing to anyone who knows the whereabouts of the missing minion.
"If somebody returns it, we don't care who, we would be quite happy to get it back," Mr Slight said.
"Just a phone call where it is and we will pick him up," Mr Olson said.