Big Spender Achievement
Purchased an item in the store.
Once you are walking around the ship 'USS McKinley' turn directly around and press on the Customize Trench prompt. A menu will come up with with various options. Scroll down to the 'Shop' option and browse through the wares. When you find something you like, press to choose the slot it will be equipped to and then press once again to buy it and the achievement should unlock.