The current cost of 1-80 hierlooms on the PTR is much higher then it should be. Teir 10-251 gear costs 695/1100 JP, whereas the heirlooms cost 2700/3500 JP.

Can you confirm that we can still do the ToC dailies in ice crown for those badges and buy heirloom items with them after 4.01/cata is released?
They'll still be available and purchased using Justice Points, and Justice Points will be the currency that drops from ... pretty much everything. Anything that dropped any emblem or badge anywhere will drop Justice Points (as long as you're of the correct level range). (Source)

On the current PTR build, they still cost Champion's Seals at the Argent Pavilion.
Yes, and they will continue to. Confirmed that there are no planned changes for the Argent Tournament heirlooms prices or otherwise.