sundown 3000d and 2 audioque hdc3 15" amp is 750 subs are around 500 Ho alternator is like $2-600 batteries are gonna be like $250. Get like 100 ft of 1/0 guage the roll should be around $100.Whatever is left on the box, and some sound deadening. solder your connections and do it right he first time.
Once you are running more than 2k you are gonna have to spend 250 to a grand on wiring and electrical.
for 2gs you could get a stetsom 7kd and 4 15" hdc3 but no way 500 is gonna get you electrical, alternator, extra batteries and the box....
you realize this question would have different answers from everyone and no one can predict your install, it all comes down to installation and patience, as well as real car audio knowledge, there is plenty of that on here, I would read this forum for 2 weeks and then decide.