Not really upgrades, but make it yours
Free: (Well, kinda, just time)
Chop /Core/ Paint stock slip ons
Slotted / Painted belt covers and front sprocket cover
Emission removal
Tail chop
Removed front mud guard, rear mud guard, and side covers
Lowered head lamp and guages
Not free: (Not much though)
K&N Breather
Billet oil filler cap (Plasic stocker leaked like crazy)
Billet inspection cover (Just cool)
Rear seat cover (Ebay $30)
Money:
Woodcraft Clipons
Thes are some things I did with out much cash, mostly time, and small amount of money for supllies (Cut off wheels, paint, etc.).
Good luck and have fun.