Yes you'll need a new esc for brushless. It's usually cheaper to get a combo with motor/esc matching. Novac and Castle make entry-level ones that you can find for as low as $140 or so as a combo for 1/10 scale.
Don't buy any more motor than you need or you'll just tear up your tranny. Loosen your slipper a little too. Make sure the motor matches the class you race as well.