Staples are offering 25% off all HP printer cartridges, plus a further 10% off if you buy 2 or more of the same item.
Free shipping if you spend $55 or more.
Staples ship to most metropolitan addresses in the country.
Obviously it will vary depending on your cartridges, but mine are $19 at Dick Smith and $11 at Staples - almost half price.
PS - I know it's not exactly 35% off because they take a "further 10%" off the 25% off price. But it's almost 35% off, and easier to round.
Don't deliver to QLD