Try putting the following CSS code at the bottom of your template, just replace each instance of #000000 with the color you want your image borders to be. This is the hexadecimal representation of the color.. if you aren't familiar with that, check out:
HTML colors<style type="text/css">
a.supersizelink {color:#000000;
}
a:hover.supersizelink {color:#000000;
}
a:visited.supersizelink {color:#000000;
}
a.supersizelink img.auctionimage { border: 2px solid #000000;
}
a:visited.supersizelink img.auctionimage { border: 2px solid #000000;
}
.auctionimage A:link{
border-width: 1px;
border-color: #000000;
}
.auctionimage A:visited{
border-width: 1px;
border-color: #000000;
}
</style>