I don't post much on here, so I'll just briefly say that I run a web marketing consultancy in Denver that has worked with several start-ups and e-commerce stores. Email in my profile if you want to talk further.
Since the discussion in this thread is turning toward whether SEO should be a "buy or build" decision, I'll throw my two-cents in there, as well.
If your website is a hobby or just a side-project, I think SEO is something you can pick up by reading some of the better guides out there (SEOMoz's "Basics" guide comes to mind). This will ensure that your site doesn't have things like <title>Home</title> or inaccessible navigation.
However, all of "what there is to learn yourself" is what our firm would take care of on day 1. The real SEO (the kind that commands 6-figure salaries or 5-figure monthly retainers) is much, much more in depth than the average internet user realizes. The reason you can't learn those strategies in a day is because most successful SEO practitioners keep them private, for obvious ($$) reasons.