I just spoke with the guy I'm doing this for...they took a more acurate measurement and the cable only needs to be about 66 ft.

I just found this DVI mini-repeater.

I'm not entirely sure it'd be cheaper though.

$150.00 mini-repeater in boost mode
$150.00 20 meter DVI-D super long distance extension cable
$ 30.00 6ft DVI-D to HDMI cable
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$330.00
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~ John