How much is a motocross bike?

Depend on what you want. With much experience, I will tell you that the better way to go is by getting one of the name brands; Yamaha, Honda, Kawasaki, Suzuki, KTM, will get you much further. If your looking at brand new ones, they can be about two-six thousand. If you look on places such as craigslist, you can find people selling them cheap, about a thousand. But still you gotta save for gas, and graphics, and everything else. Prices all depend on what you're looking at, too. Smaller bikes are usually cheaper unless they have a super motor in them. Bigger bikes are more powerful. If you're a first time rider, or not as pro, I'd suggest a 125. They're great starter bikes, just be sure to get an automatic. Switching gears could get hard.