Parents on Sydney's lower north shore are spending up to $1000 on trick or treat lollies for Halloween, as elaborate celebrations in the area continue to boom.

Mosman mother Ema Haussman said more than 1700 children stormed the footpaths of her popular Halloween street, Holt Avenue, last year.

A Halloween haven: Edward Fuzes and Anna Brandweiner, both aged 4, on Third Avenue in Willoughby. Credit:Louie Douvis

"One year we ran out of candy in 15 minutes and the following year we spent about $1000 to make sure we had enough – we barely did, which was a bit insane," she said.

"It stands to reason it's quite a financial burden on many households on the two Halloween streets [Holt Avenue and Spencer Road in Mosman] , especially if they don't buy in bulk, which I expect most wouldn't.