Similar price with Officeworks deal.
However, if you haven't used your AMEX offer 50-20. It is a good time to get the price down to less than $60.
Edit: just saw OPs update. Sorry for simply thinking it is obvious.
What I did was to buy few dollars gift card to round up n*$50 (I am not sure what is the minimum), where I can split payment by more cards.
I didn't count cashrewards yet.
This was what I did last time when Rebel had 20% off Saturday. I bought the same product at $118.xx + few things, which needs extra $8 to round up. I ended up to buy $10 gift card in order to get extra $20 off.
OPs may say gift card is excluded from AMEX offer but it works in this way for me.