Well for those bands all you need is Wah, which you have, Distortion, which iirc is in yr Wah anyway and also will be on an Amp, and maybe Chorus. You could get a Chorus pedal like a Small Clone, but I would say the Amp would be a better investment, because Chorus isn't needed that much, and you can just get a cheap (comparatively to an Amp) pedal anytime.
