Any motorcycle shop to buy a new one, Craigslist.com is an awesome place to find used bikes. You can also usually look on Motocross fourms such as mxcrazy.com depending on where you live. Ebay? That's all I can really think of.
There are numerous places on can find dirt bikes of sale online. One can find dirt bikes to purchase on sites such as 'Cycle Trader', 'MotoBuys' and 'Want Ad Digest'.
yes, dirt bikes are motorized
NO dirt bikes are either air cooled (you will mainly find this on Chinese bikes) or they are cooled by coolant from a radiater, much like the one in your car.
dirt bikes
Everybody that races dirt bikes "started" racing dirt bikes at some point.
dirt bikes in the past had less gears and power then dirt bikes have today
no dirt bikes arn't illegal
no there not dirt bike is better
The two main types of dirt bikes are motocross and trail bikes. Yamaha, Kawasaki, and Honda all make these types of dirt bikes.
dirt-biking is for dirt-bikes it can be either stunt or mud riding
There are a few dirt bikes that you can buy that are cheap. Some generic dirt bikes you can buy are 200 CC, Yamaha and you can have bikes shipped to you from China.
Yes Dirt Bikes Have Vin Numbers.