I went to a pawn shop last November and bought a pair of 15" Earthquake Magmas (very old model) in a ported enclosure for $50. The guy said they were worthless because the rubber gaskets were missing and the box was in such bad shape. Nobody would want a pair of speakers this ugly, he said. They did look pretty bad...at first glance, but there was potential there. The missing gaskets, dirt and beat up enclosure were hiding the fact that these were actually some very good old school subs.
I added a front baffle to the enclosure that sat flush with the high roll surrounds. It hid the missing rubber rings and gave the box a "custom" look. I then added some bracing and resin to the internal area, hit the entire box with a belt sander, rounded everything off nicely and sanded everything smooth. I finished up by re-sealing the box with liquid nail, painting the new baffle grey and adding black carpet to match my friend's interior.
$50 bucks, an evening of my time and a roll of cheap Wal-Mart carpet turned into a very nice christmas present that flexes the roof of my friend's vehicle...