I havent looked at the site mentioned, but there are some legitimate traffic sellers out there, who do provide real hits etc....

Mostly the traffic is delivered by popups/popunders....or through re-directs from expired domain names.....

I have not heard of many great success stories from purchased traffic....

I once purchased around 20k visitors for a new site/product that i launched.......didnt get one lead out of 20,000.....

For the same site promoted using adwords, the first lead was obtained with less than 100 visitors.....