As I wrote earlier - the Spektrum radio kit from rcmart comes with two servos: 270 and 590.
You can use the 590 for throttle. The 270 is too bad to use.
For steering you should get a Sanwa erg-vx or Sanwa erg-vz. Normally you can find them at rcmart, but not at the moment.

When looking for a steering servo you look for both speed and torque.