it is not hard to get loud with $400-$500. here is a break down.
build you own box. roughly $30 for a sheet of mdf and $5 for a box of screws and $5 for glue.
you can get 2 good 12's for around $200-$250. and a amp to push them for around $150-$250.
to put it in perspective. my wife's car has 2 american bass xfl dual 4 ohm 12's which were $225 brand new.
she has a crunch p1500.1 which was $185 brand new.
i built the box which was $32.87 after tax for a full sheet of mdf.
her amp kit would have been $20 brand new.
all in all i have less the $470 in her car. she does a 147.6 @ 48 hertz. i kept the factory HU in there and left to bose system as well. she has a '00 GT.
