I don't look at the cost of the line when factoring in my yearly profits. To me the initial cost of the line is more of a long term investment. Line values are climbing, they have been for the last 40-50 years. Just like land or houses, the value will continue to rise.
If I can break even or turn a slight profit on my line every year I'm pretty happy. I am always looking for ways to increase my gross annual income however