Interactive Brokers generally does not negotiate...they use "Wal Mart" type pricing (i.e. everyday low price). However, TD Ameritrade, E*TRADE, Fidelity and Schwab will negotiate if you can hit minimum asset levels and share volume targets. There are some people who don't pay any commissions on E*TRADE or TD Ameritrade, although I'm sure they pay more than zero for margin interest.
Would you know if E*Trade or TD sell order books to HFTs? That is something we debated briefly on my previous post