Buying traffic for you website is just a new twist on the old system of buying email addresses years back when people were selling by spamming. It's just a rip-off. Even if they could send traffic to your site, it would not be targeted traffic and you would get no sales from the visitors..
Instead try linking your site to other sites and installing so good keywords in your web pages, (content pages) try using the key words in multiples of 2 or 3. Don't try to just put in a bunch of mumbo jumbo content pages with keyword spamming, but instead use the content pages to describe your products. Things such as the benefits of the product, it's specs, features and things like that..The spyders will locate your site and give it a much better ranking by doing these things...