I've just read through this thread, and I find it very interesting, man. I don't have much to add, though - I always buy lettuce at what apparently is the cheapest grocery store in town (I like their tomatos and oranges a lot). They have various types of lettuce, so I go with whichever I think looks the 'nicest' that day. Maybe I should learn a bit more about what I eat.
I hope this small business works out for you - you clearly seem to know (and enjoy) what you're doing.
Also: is $0.80 a normal prize for a (good quality) head of lettuce where you live? Or is it really cheap? That's approximately what I pay (although I live in the south of Argentina, and it's the summer, so this probably is a stupid question).