You key issue should be execution. At 15 cents/contract they must have some payment for order flow (no issue to you) or must have a smart router that will hurt your best execution. A lot of exchanges (especially the ISE - the most liquid) have maker/taker fees. If you are trying to pay bid/offer they may not route your order there. You could find that your executions are delayed or not happening as they try to source liquidity on an exchange that is free.
If execution is an issue for you, you should investigate these guys more. If it's not, then the price seems great.
If execution is an issue for you, you should investigate these guys more. If it's not, then the price seems great.