Uh....okay. Went back and looked at the original post. I didn't get it wrong after all. The original poster attached a link showing a seller selling non-custom banners on ebay.
They are not "stupid low" prices at all. I think they're fairly priced...given the fact that these are not custom.
That's where the time comes in. Layouts, sales time, back and forth with the client etc.
I guess I stand by my comment. For non-custom work, I've no gripe with the seller. We do a very similar thing on the internet (as I stated).
I'd take that work all day long if the orders simply streamed in via the internet.