The following outfits can be unlocked to purchase from the store in career mode:

Unlockable - How to Unlock

Axel's No Shirt - Complete every song on a CD on expert mode.
Axel's Other Shirt - Complete every song on medium mode.
Gunner Jaxon's Random Junk - Complete a song on easy mode.
Gunner Jaxon's Whatever - Complete a song on hard mode.
Johnny's Anarchy - Earn 5 stars on every song in a CD on hard mode.
Johnny's Ink - Complete every song on easy mode.
Judy's Flashback - Complete every song in a CD on medium mode.
Judy's Pirette - Complete a song on expert mode.
Memphis Rose's Biker Gal - Complete every song in a CD on hard mode.
Memphis Rose's Recruit - Complete a song on medium mode.
Pandora's Bad Apple - Complete every song on a CD in easy mode .
Pandora's Lace - Earn 5 stars on a song on hard mode.