Requirements:
Level 78. The T-Bone Steak unlocks at level 78.
A minimum bankroll of 172,500. The Steak costs 172,500.

Method
Start a one million buy-in table in single player mode. While playing press "X" to access the store. Locate and purchase the T-Bone Steak. Once you confirm the purchase the achievement should unlock.

Important Notes:
In single play you do not need 1,000,000 to start a one million buy-in table.

Keep an eye on the Weekly Promotion Boost. If the T-Bone Steak is in the promotion then you get a considerable (50%) discount.

[Recommendations:[/b]
I would suggest to get this achievement AFTEr getting the "A cool Million"-achievement.