You can buy those high end bikes, and they are specifically made for what the rider is doing. The only thing is they are EXTREMELY expensive bikes. Some high end dual suspension downhill mountain bikes can cost upwards of $8,000. Unless you have THOUSANDS of dollars to spend on a bike, your son isn't getting a bike like that. You can purchase bikes like that, but the price is so high your son would not be able to appreciate a bike like that until he can ride as well as a pro rider can. Pro riders have bikes that expensive to meet the needs of what they do. I guarantee you he does not need a bike like that.
This is just one example.
http://www.trekbikes.com/us/en/bikes/mountain/gravity/session/session_88/#