I had an account with OEC until they started charging DOM fees and inactivity fees.
With a funded futures trading account, typically you will pay 5 to 15 USD per month for Chicago Mercantile Exchange (CME) fees. Without a futures trading account the costs can potentially go up to 378 USD per month (94.5 USD/month for the CME, CBOT, NYMEX, COMEX each) if you want access to all of the CME futures contracts across all four market data centers in real-time. However, for the major stock index futures (like ES, NQ, and others), the cost will be 42 USD per month for the CME exchange fee if you do not have a trading account.