Several have already said once you start paying for link building, you are no longer using white hat which I totally agree with. If you truly want white hat, you have to engage people to link to you. Meaning you have to have value, you have to be the expert on your topic, or atleast be perceived as so. Use social media to find people interested in your topic, then use other avenues such as info graphics or whiteboard video to engage them and get them to post, like, tweet, mention on their blog, etc.
If you want to be strickly white hat and spend some money I think its things like infographics/video give you a CHANCE at getting people to pay more attention. Additionally you can invite other "experts" to guest post. You can find people like that on LinkedIn for a lot of Niches.