i have rockford amps 2 260.2 and 1 160.2 amps which were used for like 3 months and been in storage ever since. they are the new styles. i also have like $400 to throw on top of that. let me know.
i got two Rockford fosgate subs in a box that i will sell you for $200. they have been used for about one year and are still in great shape. They are series one, 4 ohm i believe and i had a 800 watts running both of them, which blew my trunk open a couple times. If you want to know more let me know at brandonladell17@hotmail.com.
what amps are you going to have to push 4 15s?? .. and what vehicle.. you prob should only stick w/ 2 15s, that way you can build a bigger box and have less power, or feed these 2 subs more power..
ive got 4 mtx 6000 15's i bought them off ebay and have never hooked them up i'll sell em to ya for $400 + shipping if your still interested email me at chapy4650@aol.com