Found this while browsing the Brother website. The max rebate is $300 off a RRP$1,000-ish Multi Function Printer, so not too shabby - but when combined with HN or GG, you might be able to get an even better deal (true OzB style!).
Anyway, I'm still trying to find my own combination which will work, but thought I'd better share!
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For a limited time purchase selected Brother products and receive up to $300 Cash Back*.
Offer available from 1 November 2015 to 29 February 2016 on selected MFCs, Printers & Scanners.
ELIGIBLE PRODUCTS & CASH BACK AMOUNTS
LASER
MFC-8950DW $300
MFC-L9550CDW $200
MFC-8910DW $100
MFC-L8600CDW $100
HL-L9200CDW $100
HL-L8350CDW $100
HL-L8250CDN $100
HL-6180DW $100
MFC-8510DN $50
DCP-8155DN $50
HL-5470DW $50
HL-5450DN $50
HL-5440D $50
INKJET
MFC-J6920DW $100
MFC-J5720DW $50
DCP-J4120DW ~ $50
MFC-J4620DW $50
MFC-J880DW ^ $20
SCANNER
ADS-2600We $100
ADS-2100e $50
~ The DCP-J4120DW is a Harvey Norman exclusive model
^ The MFC-J880DW is a The Good Guys exclusive model
IMPORTANT:
• Claims must be made online by 8th March 2016 and supporting documents must be received by no later than 31st March 2016.
• Officeworks is a non-participating reseller
Also good to know that payment is made within 5 days of approval, so not too much waiting around unlike other cashback promotions.