Reach the indicated level to unlock the corresponding booster for purchase in 
Multiplayer mode:

  Bandoleer (Booster Slot 2): Level 4 ($2,000) 
  Break Up (Booster Slot 1): Level 10 ($11,250) 
  Come Get Some (Booster Slot 2): Level 58 ($2,000,000) 
  Deposit (Booster Slot 2): Level 40 ($98,250) 
  Down the Irons (Booster Slot 1): Level 14 ($18,750) 
  Evasion (Booster Slot 1): Level 50 ($210,000) 
  Explosive Expert (Booster Slot 2): Level 20 ($32,250) 
  Fleet Foot (Booster Slot 2): Level 16 ($23,250) 
  From the Hip (Booster Slot 1): Level 6 ($5,000) 
  Glass Jaw (Booster Slot 1): Level 56 ($1,500,000) 
  Half Loaded (Booster Slot 2): Level 54 ($400,000) 
  Hell Blazer (Booster Slot 1): Level 18 ($27,750) 
  Invalid (Booster Slot 1): Level 52 ($350,000) 
  Juggler (Booster Slot 1): Level 38 ($94,500) 
  Keep Firing (Booster Slot 2): Level 12 ($14,250) 
  Launch Man (Booster Slot 2): Level 28 ($58,500) 
  Monkey Man (Booster Slot 2): Level 32 ($72,000) 
  Point and Shoot (Booster Slot 1): Level 2 ($2,000) 
  Rapid Hands (Booster Slot 1): Level 42 ($111,000) 
  Revenge (Booster Slot 2): Level 48 ($134,250) 
  Rocket Man (Booster Slot 2): Level 44 ($120,000) 
  Scavenger (Booster Slot 2): Level 8 ($8,250) 
  Scoped In (Booster Slot 2): Level 36 ($87,000) 
  Situational Awareness (Booster Slot 1): Level 46 ($129,000) 
  Sure Foot (Booster Slot 2): Level 26 ($52,500) 
  Sure Shot (Booster Slot 1): Level 30 ($64,500) 
  Treasure Bearer (Booster Slot 2): Level 24 ($43,500) 
  Turtle (Booster Slot 1): Level 22 ($40,500) 
  Veiled (Booster Slot 1): Level 51 ($300,000) 
  Walk Softly (Booster Slot 1): Level 34 ($79,500)