You can buy one from a local dealer, or you buy a used one from someone selling in a private part situation by checking classified ads, just do the research to find the appropriate size for him/her and what you think the can handle.
Snowboard because its better than a dirt bike.
Buy a USED 250 dirt bike.
For a 2-stroke dirt bike all you have to do is, buy a taller cylinder, and buy a longer crankshaft.
Not usually. Some dealers will give you a helmet when you buy a bike, but nothing else.
One can buy a mini dirt bike from the local bike stores. Sometimes local community auctions also feature variety of mini dirt bikes for very reasonable price.
Auto Zone
you don't!!
Ebay, Craigslist, a dealership
buy a Giovanni kit bike and follow the instructions
50cc dirt bike may be available at a bike specialist store, but very unlikely. Most 50cc dirt bike are seen online for purchase only. For example eBay and Amazon.
Dirt bike parts can be purchased at several retailers. These retailers include Service Honda, Rocky Mountain ATV/MC, Dennis Kirk, and local dirt bike dealerships.
the excitement and freedom