kdrifter i seriously doubt u are likely to find a very good water cooling setup, already built, for under $100. anything u find in that pricerange is gonna be crap, as is that ebay product u linked to earlier. as jas mentioned, your best bet, although still unlikely, would be to build it yourself for under $100.
less than $100 cash is not really enough to consider watercooling in my opinion, however as little as $200 could build a very nice setup. the people in this forum obviously favor custom built water systems, so information on quality premade systems is rare (if any exist at all).
after all, this forum is full of people who built thier own system, so thats where the wealth of knowledge lays