I have run line out converters before and i was never really happy with the sound quality from a stock head unit. I had a Sable with digital clumate controls, in order to go to an aftermarket head unit you had to get an $800 dash kit. So I had to run the converter, I also had a selectable line in for my satelite radio. Adding the Boston speakers plus two 10" subs in the trunk, all run by a LJ amp was a good improvement but still not nearly as good as RCA control out of an aftermarket head unit. In my current car, I have the same amp running Alpine fronts and suby rears plus the same subs off of an Alpine deck. There is such a big difference. Just so much more control and variability.
If you are still stuck, I would be happy to give you a hand. Seeing as how you are practically right up the street.
It's been a while but I seem to remember something about the speakers are high voltage and an amp needs low voltage, which is why you MUST use a converter. I might actually have something still, I can't remember. The next time i drop by my folks place i can take a look. But sanford sound should have what you need.
-----Added 8/17/2009 at 10:51:09-----
well what u got im lookingf or around a 600 watt amp and a 10 inch box and most likely the line out converter.
Are you looking for volume or sound quality? I am not a volume guy (or a car audio guru), but I think a 600 watt amp for one 10" would be a little overkill. Not that there aren't subs that need 600 watts, but to get a good punch that won't bother every other driver, you don't need that kind of power. And of course the converer is going to be what costs you the least $ out of all that stuff.
Now that I think about it I have a whole bunch of wiring stuff, power wires, ground wires, speaker and rca's out of other set-ups. Before you by anything let me know what you need and I'll see if I have something we can coble together for you. I have a fetish for doing "clean" installs so I would basicaly buy all new wires for each new car. And I have had the same subs, in the same box since high school.