Pheonix Gold 5.25" Octane R Components ($185)
Best components at the price point, I believe. 5.25" diameter should facilitate kick panel mounting.
Audison SRx3 amplifier ($625.00)
Great three channel amplifier, essentially a two channel stereo amplifier with a separate monoblock built into one housing sharing a power supply. Third channel will load down to 2ohm and dissipates 310W RMS at that impedance.
Pheonix Gold Octane R 12" DVC subwoofer ($189)
Again, a good speaker for the money. DVC (4+4) will allow loading down to 2ohm, drawing 310W RMS from the amp suggested above. (Subwoofer is rated at 250W RMS)
Add a deck and you're set - something like an Alpine CDM-9801 can be had for $300 if you look around.