Unless you broaden your definition of spam. I believe I can be spammed by legitimate companies of which I am a customer. For instance, GoDaddy, Amazon, NewEgg, et al spam me all the time. It's not that I don't enjoy their products/services, but they are emailing me unsolicited advertisements (yes, I know I can opt out). This is the type of spamization I am referring to, not Nigerian scams, Viagra ads, and the like.

I don't think $1 / message is prohibitive for a GoDaddy or an Amazon.