To my mind, good SEO is explicitly expected of the Web Dev/Design team. They are not earning their paycheck if they don't build in good SEO stuff. That said, we also have paid outside people to work on our SEO needs.

Further, we see PPC as advertising that is directly related to generating sales. SEO might address soft issues of usability and how people feel about the site; PPC is just for getting targeted clicks to make people buy our stuff.

If I had a limited budget, I'd most likely go for SEO for the long term benefits. But some days you just need to move merchandise, in which case PPC is the way to go.