Pulled this from Bigw website... and bolded my locals (you know where you've seen me shopping swoop....)

In-store layby

For a layby placed in a BIG W store, we require a 10% deposit and a $5.00, non-refundable service fee for a 10 week term (full details available here). Fortnightly payments are required, or the in-store Layby may be cancelled. Interim payments may be made at any front-end checkout in the store where the layby is held. Extended layby periods are available at selected times of the year and we offer extended layby periods for aged pensioners. Please contact your local store for more details.
(Excludes seasonal clearance, discontinued items and selected products (perishable goods and chlorine).

In-store Layby is not available at the following stores:

QV Melbourne store
Box Hill
Doncaster
Canberra Civic
Auburn
Macarthur
Karrinyup