From my limited knowledge, it would be a lot better for you to buy the actual bitcoins themselves and hold on to them to maximize your profit(if you believe the price will keep rising)
Obviously thats the best response but people that are not familiar with the concept of difficulty in mining think of miners as magic machines that convert electricity to money. I don't know why they don't ask themselves if that's the case then why companies are selling them and how they choose the price...