For most traders, commissions are going to be much less important than slippage. Slippage is basically paying the bid ask spread every time you trade. In essence, there is a cost of transaction, even with limit orders, because most of the time, it will not get filled unless the bid goes sellers or offer goes buyers.

The only way I see to limit your broker wealth on your behalf is to:

1. Buy/lease a seat at the table (doesn't help the bottom line unless you trade huge lots), or
2. Cut your entries by 2/3, by whittling down your system to only the high-probability trades.