I believe the DTN IQ feed is the cheapest real time data to run with it, although you can hook it up to IB's data for free if they are your broker, but you don't get every tick that way, and I'm not sure about any historical data. You get ten years with the DTN, and several months intraday.
IQfeed is 70 bucks for the real time futures package, I think. Then you have the 10 to 15 bucks on top of that for eminis. I am not sure about this as they may just throw in the minis for the $70. I have other exchanges, so I pay more.
You can also use Signal data at more than twice the cost. Identical in speed. Not sure if it is cleaner. I have used both, and both have the occaisional bad tick.
The DTN feed has been interrupted on me only one time. Used to happen quite often when I used Signal. Haven't used Signal for about 2 years though.
Jay