It all depends on your trading style (size, frequency, etc).Quote from madbrain:
That's not bad, I probably would use the former rate. I wouldn't have >30 contracts and likely the max rate would be $13 with 30, then.
Yeah, I looked at IB's commission page. 0.25 is pretty good for the cheap contracts. But 0.75 is on the higher side of things. Commission would be $22.50 with 30. Free assignment/exercise is very nice, though. I have to check what it would cost at optionshouse. I'm more concerned about assignment. I will have to start adding commissions to my spreadsheet and see the costs.
For me, per contract rate is best since that allows scaling in/out without that pesky flat fee per trade (t)humping.