What percentage of revenue comes from SEO vs. SEM vs. sales people for SaaS companies?
These are our experiences with WebEngage.com 
(100% self-serve freemium SaaS product focused on SMB's and enterprises) -
Most of our enterprise customers were acquired through direct sales (f2f meetings/demos etc). About 20% of these were inbound queries.
We are an in-site survey/feedback tool (very unique in terms of appeal and utility). A bulk of our prospects (almost 40%) find us on our customer's website by clicking on the "powered by WebEngage" logos in the feedback and survey windows. This accounts for most sign-ups on WebEngage (free as well as paid).
3.Referral traffic and leads via inbound marketing accounts for the next big chunk of sign-ups (almost 25%). People discover us on third party blogs, review sites etc.
4.SEO comes in next. It is way more inexpensive and long term. We are amazed to see the kind of queries people use to discover us on Google. Analyzing that data and incorporating the learning back into our product/UI has really helped over a period of time.
We are just 6 months into WebEngage and have no money to spend on SEM :). I am sure once we have start spending a bit on marketing, the numbers above will change.
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