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The thing is I am extremely happy with the results I am getting, the money coming in far exceeds the money going out, and even though it has only been 5 days, I am confident that I will try to get more traffic coming in for similar terms that I wasn't so sure about originally.
I experimented with keywords I thought might be off focus and low and behold, they are profitable as well. I think it is totally worth it if your landing page does the sale. If you're just sending traffic to a site hoping sales will come through you'd better have deep pockets, cause it can get expensive fast.