RC stuff like that is expensive..... I have a couple small electrics and I have hundred into them. When you start getting into big scale stuff its in the thousands. Then if you do jets the engines alone are close to 8k each. Just like any hobby, you can spend a little or spend alot.
Heres another one 4 jet engines
http://www.youtube.com/watch?v=zUyR0eezwns&NR=1
Theres one that had 8 jet engine and it crashed on it 1st or 2nd flight.