SEO is a pretty saturated field, but this is a good domain. I have SEOHandyman.com which I am real proud of but it has not attracted anything in the way of offers yet. Anyway, your SEOTutor.com would be great once developed as a tutorial site, even if it is a simple one, then I would value it in the low $xxxx. But while undev, I would have to give it low (to possibly mid) $xxx.
I know SEO is fairly popular but I don't see a lot coming from the domain. It's still worth a fair amount though. I'm going to appraise it from $100-$125.
Good Luck!