Is there any other way to receive these television channels?

I find myself limiting my television viewing to educational channels like ID Discovery, Science, National Geographic, History, Military, and Biography. I currently receive them via a cable television company. But that is expensive considering how few channels I watch. To help reduce expenses, I've looked into Dish Network and DirecTV satellite services. Are there any other options available to receive these channels on my television or view these channels on the internet?