taodr,
"IB and size"; I thought size didn't matter ... never mind, that's something else ...
I also regret that IB has priced itself out of large orders. I've confronted this problem and have been looking to take my business to less expensive brokers. The following is the information that I have to date. I moved part of my account to rjt.com (who had recently been purchased by T. D. Waterhouse) because they seemed to have the lowest commissions for an unlimited number of shares. It's $9.95 for market and limit orders. However, all was not well when I found out that if you trade during pre- or post-market, then there is an added cost of 1 cent per share. This definitely is not good, as I like to use these times to get out of positions, on occasion.
I have recently learned that Ameritrade has one set commission regardless of number of shares, viz., $10.99, and furthermore this is also true during pre- and post-market. I was assured by them that there were no extra costs. They had recently merged with Datek.
Another brokerage to consider is Scottrade which charges $7.00 for market order and $12.00 for a limit order for an unlimited nimber of shares. I don't know if they offer pre- and post-market trading, and whether the commission changes.
Also Brown and Co. (
www.brownco.com) has $5.00 market orders and $10.00 limit orders for up to 5,000 shares. After 5,000 shares you pay 1 cent per share retroactive to the first share, so that the commission on a 6,000 share market order is $65.00. Obviously, it's better to issue 2 orders and pay $10 in commissions. They also offer pre- and post-market trading, and it appears the commission structure is not changed during these times.
Cybertrader.com has commssions of $9.95 for up to 5,000 shares. After that the commission structure is complicated by a whole bunch of rules. Best to check their web site for this.
I hope this helps. Please let us know where you end up.
Richard