No, but how much is 50% of your total website traffic worth to you?
Similar to almost any other profession, you can do it yourself, but will always see the best results when you bring in experts to help. You can do your business’ taxes on your own, but choose to hire a professional because you know that they will be worth the investment.
If your business’ marketing budget is less than a few hundred dollars per month, take the DIY approach to SEO. Any “expert” charging less than a few hundred dollars per month is going to be a risky investment. They may land you in some hot water with Google.