The AstroFlight comes with a speed control. Not sure what, if any, batteries you have now.

I'd also check http://www.ezonemag.com/ . Recently there have been some new brushless motors come out that may be as good at a lower price. But honestly I haven't compared the prices vs. power on these new motors to the AstroFlights.

The brushless motors are more expensive, so you may also explore some other more powerful brushed motors if you can't afford the $$$ for the brushless versions. Be sure to include the cost of the speed control in your comparisons because some brushless have the speed control and brushed motors normally don't.

Also, keep in mind that the brushless motor will never wear out and will provide much more run time and more power on the same batteries because they're much more efficient.

Good Luck,
Keith Black