If the market is willing to pay you $X (at most) then that is your market value. Not more, not less. If you see someone getting paid $X, you need to try and figure out how he/she got there. Why put your efforts/thoughts into how you can drive down that persons salary?

There is no such thing as over paid. Just what you are willing to accept given your constraints. With the current H-1B system there are constraints. In particular, job mobility, that restricts you from easily taking a higher offer (the legal hoops that you and the future employer have to go through is a burden).