Short answer, no. Not worth it.

Focus on generating profitable leads.

If however you're still hell bent on going the SEO route, focus on profitable and high converting keywords. How does one do that? By doing a PPC campaign and then watching which keywords convert. Then do SEO based on keywords with buying intent.

Far too many times I have seen people spend a lot of money on keywords that get a lot of traffic but have very little buying intent or conversions. It's not about how much traffic you get, it's about how much quality targeted traffic that converts.