As you earn money, you can buy cool extras / cheats from the main bar area:

purple - 50,000
silhouettes - 75,000
big blasters - 50,000
classic blasters - 75,000
silly blasters - 100,000
moustaches - 150,000
minikit detector - 750,000
teacups - 175,000
brushes - 200,000
invincibility - 1,000,000

Main Star Wars Lego Walkthrough