Paying for Link Building can be expensive. 
Is it worth it. Well that depends on your goals. If you want more traffic to your site then link building can help you out and the resulting sales should offset the expense. You need to hire a reputable SEO Tech to get the desired results. If you are considering link building as a solution for your business then you are not alone. I would bet that your competitor is using link building and you need to as well to stay in the game. Kimra Bettasso can attest to the effectiveness of link building.