Under our current system the way to accomplish this would be to use the countdown timer on your Pages. Have the page automatically redirect to another page when the timer expires. This has the advantage of being able to show a countdown clock to the next pricing change to give a sense of urgency.
Page one could be the 10% discounted price that works until 2 months before your cut off date.
It redirects to page two at 59 days before the cutoff date. Page two has the 7% discount.
When the timer expires on page two, it redirects to page three that has the 4% discount. And page three in turn redirects to page four when it's timer expires.
The disadvantage is that the multiple redirects may cause the page to flash and delay loading of the page.