Ya building a list is pretty key. I've heard so much noise about it in the past so I know how crucial it is.
If anybody can build a big list then that person can be benefited. But I think its very hard to build a list in a shorter time. I dont want to spend more time for list building. So, I think using other free traffic methods are the better alternative for getting more traffic. From my opinion posting ads on facebook and free classified classified ad sites are the better options for driving more free traffics.