* find out what size FRONT speakers u can put in the front section of your car.. be it in the door or kick panels.. most probably 4' or 6' .... get a pair... (get splits... i recommend this). dont get 6*9s
* get your 12' sub
* get a 4 channel amp to run the sub (bridged) and the front speakers. Note about amps.. get one with crossover built in ...
And generally... a $400 'no name' amp will do a good enough job to power your system.. if you are not a SOUND GURU..
$400 on a brand name amp will probably get u a shit one... so u can buy a $400 no name ... or spend a little more to get a decent branded amp...
speakers $150-250
amp $400
deck $400-500
sub and box $200-300
wiring $60-80
Install - DIY of course !!