These Crystal Mobile come in under your $400 and sound very nice. I have them installed in my car.

Last years model are only $119 from Sounddomain . Great Buy!!

Otherwise if you want to make your own I would go this route. Some custom fab will be need but well worth the very little trouble!
Digital Designs W6.5
VIFA XT25TG30
DDXO-HP crossover

1998 SE ATX
Dual exhaust
Body conversion
Nakamichi CD-40z HU
Sound by Crystal Mobile
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