http://www.cablewakeboard.com/index.php?option=com_content&task=view&id=35&Itemi d=49 i took you straight to what you asked for, but this entire site has everything you will need to know. bottom line, you will need about 1 million to even think about it. there are lots of logistics, insurances, permits, etc, but this site tells you all you need to know and what to contact. (digging your own lake is possible and even mentioned, check it out)
i say build it if you have the cash and backing. i live in nashville. people would come from miles around and you could get easy and heavy use for a full 8 months out of the year. the nearest one, orlando, would still be a good 8 hours away.
if you didn't have that much money, a flowrider might would be a cool cheaper option. once again, a real moneymaker i believe. build it indoors and use it year round.