I have seen the "Submit an Offer" as well. I haven't won anything with it, but each time I submitted an offer that was too low, I have received an e-nail back explaining what they spent for it, or about how much they are expecting.

I see it much like when someone puts a For Sale sign in a car, and when you inquire, they always seem to ask "How much will you give me for it?". Buyer starts low, seller starts high, and meet in the middle.