i wouldnt amp the fronts then just buy a sub and a mono or 2 channel amp you will be good to go.amping the fronts will over power every thing.i know your on a budget so give this a look i belive it fits just what you need http://www.audiosavings.com/products/Car-Subwoofer-Amplifier-Packages/RE-AUDIO-12-SUBWOOFERBOXSOUNDSTREAM-DI175.1-AMPKIT/SBREX12D4---DI175.1---XK8Z.aspx