You are saying it from your own experience or it's just what you heard or read somewhere.
But if you need alternatives, then I have some recommendations. I don't know what you are selling, but I think that Google Adwords can be a good choice to advertise product, but you have to choose targeted audience carefully to find people who can be interested in your product. Otherwise, your advertisement will not be effective and you just waste money.
For referral links you can just create website or blog to promote these links. Also, you canadvertise link via bitcoin ad networks - it's cheap and effective way for advertisement. And still, nobody invented better method to promote ref links than forums and social media.