I'm going to throw a flag here. Having fun with a question is all well and good but when you tell a 14 year old to start selling weed, addict his friends, on and on you're just plain wrong. Not funny, not cute - plain old wrong.
kawasaki4life,
You sound like a sharp kid with a lot on the ball. Not every 14 year old is sharp enough to stare into the future, save his money a purchase something he wants. I say buy new because you are guaranteed to at least get a safe bike. A helmet, front brake, front and rear lights should be easy as pie to get as Christmas presents - and I mean the good stuff. Go shopping at you local bike store and tell your mom, dad, aunts, uncles, grandparents, etc. what you want. Choose a real nice helmet.
Not everyone on the internet is actually older than you and as you've already seen on this thread not everyone is as mature as you. Keep your smarts about you. Sometimes, especially when you are 14 being dumb can seem cool and being smart (like you) seems boring or uncool. Please just believe me when I tell you that staying smart and mature (again, like you are) is exactly what you want to do.