You can earn 1 point for every 100 bells spent at Tom Nook's store. They can be used to earn the following prizes.

Unlockable	How to Unlock
Bad bro 'stache	2,500 points
Banana	500 points
Hero's cap, Majora's Mask, or Samus mask	6,000 points
Hero's clothes, Varia suit, or Wario hat	5,000 points
Kart	10,000 points
Midna's mask	6,500 points
Peach's parasol	4,000 points
Toad hat	3,000 points
Triple Shells	800 points
Yoshi's egg	1,000 points