hmm. That would depend on how much time you've got on your hands. Traffic for your own website is either time or money. So assuming you've got time, then the best source of traffic would be from the search engines by ranking well for targeted keywords. It also depends on your business venture, though. If you have something to sell, and you don't want to mess around with a website, then you can get instant exposure for your product by listing it on eBay or a niche classified site. That way you are using someone else's traffic and some of the classified sites are free.