The price shown is on Tab Large, Apple makes Koodo show the lowest possible price on the website. If you use Tab Large you'll have to pick a tab large plan as well. Those start at 65$ and go to 95$ all of them also have a tab charge of 10$ additional per month.
Tab Medium will take 300$ off the retail price of 450$
So you'd need to pay 150$
And you can have it with the plan you mentioned at 30$ (plus a 5$ monthly tab charge) a month