Everybody wants a brand new kart, if you don't, your lying! But there is always the money constraint, and in a tough economy, it hits even harder.
Some say buying new makes sense for you, as you will avoid getting bad equipment. But then there is also the risk of not "being into it" and losing out on a lot of money.
You'll hear opinions both ways, and of course a kart dealer will say buying new is the best. He may be right, or he may not be. It's up to you to decide. If you have a lot of friends in kart racing, then you can trust their opinions on what to do and that is always the best thing to do.
Buying new may be a nice upgrade for you. You probably know what you want and how you want to achieve it.
As with anything, research and talk to other people that have the type of kart you are looking for. They can be a valuable source in helping you make sure you like what you buy.
Of course if they are a competitor that may not like you, be careful what you get.
Well, it can come with whatever you like. Most places will offer a body, wheels and tires if you like. They usually call the fully loaded one a "Championship Edition" or some other strong title. Of course you will see the price increase as well.
If you have all that stuff already though, you could just buy the frame with steering and spindles.
A new chassis can run anywhere between 2000-4000 or more, depending on what type of kart you get, and lots of other factors. Do your research, they are mostly around the same prices really, as they are competitive.
Buying a new kart is a good investment if done smart. With all the new designs and technology in newer karts, you will probably be getting an upgrade in speed, or at least the ability to adjust factors like handling at greater ease. You probably already know that of course though if your experienced and looking for a new kart.