i just recently invested in a small sound system for my 96 honda accord ex coupe. i bought an 2 ch amplifier and i plan on bridging this to mono and getting the full 600 watts to power one subwoofer. my question is... is this going to take too much away from my battery and will i need an alternator?

also does anyone know of any good 6 1/2 in. speakers for under 80 dollars? i just need to replace the factory speakers and they dont have to be great