If you have the budget and the patience, then buying traffic is the way to go. You do have to remember that as a marketer you do have to test and track. This means that more times than not you will lose money when buying traffic until you get to the point where your campaigns are profitable and your funnel converts well. Ideally you want to make sure that your funnel converts well enough before you buy traffic so that you break even at least and get opt-ins.