I echo your choice of "green smoothies" - they're an outstanding solution to the cheap, fast, and healthy requirements. Though like you, the reactions I get from people generally involve disgust, even when those same people will happily pay $4 or $5 for essentially the same concept/drink at a health food store, for a quarter of the quantity and quality. Hell, half the drink may be ground-up ice and they only get half a banana too.

Most people are not rational, especially when it comes to food.