Buy Everything At Computer:

Step 1: Enable the option
Step 2: Use the computer.
Step 3: Click the double arrows to the right of Weapons.
Step 4: Click the X to the left of Homeland 37
Step 5: Click the double arrows to the right of Manuals.
Step 6: Click the X to the left of Pistol Belt.
Step 7: Click Checkout.
Step 8: Click Checkout.

You should now have everything unlocked.