Iron, you are correct that the cap increases by 5 aa cost per tier, and it should be something like 3, 6, 9, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, which should be 443 per trade. Also, the last rank is level 105.

After you reach 300, you can not advance simply by making non trivial recipes....