Tahoe,
Its been my experience that you will have a hard time finding "hard and fast" rules that you can get for free (that work, there is plenty of free crap for the taking...). I agree with you that you shouldn't pay for buy and sell signals. I would go one step further and advise you against buying any system, even if the rules are fully disclosed. There will be those here that disagree with me (although I think the majority of mechanical traders will agree) that there is nothing for sale that is worth trading over the long term. Most of what you find for sale will have been over-optimized to show fantastic past performance, only to flop when traded real-time.
At some point in your search you will come to the realization that the only way to have a profitable mechanical system is to develop it yourself. I see from your other posts that you use Metastock, so you have a powerful tool to help you. I think there are some limitations that may make you want to switch down the road to something a little more flexible like TradeStation or Ensign, but MS should be plenty for finding ideas that work. And I'm not talking about their built in systems, they don't work very well.
I don't know where you stand in terms of knowledge of system development, but a good place to start is by reading "Trading Systems That Work: Building and Evaluating Effective Trading Systems" by Thomas Stridsman and "The Encyclopedia of Trading Strategies" by Jeffrey Owen Katz and Donna L. McCormick. Those books will give you a good idea of how to go about developing your own ideas, and some prefab ideas you can test out to get you started. (Note to Alex: There are some sample systems in these books that will give you an idea of how to go about building your own). Always keep in mind though that simpler is better, and there are no magic indicators.
Its a long, difficult road, and you will get discouraged many times, because the bad ideas far outweigh the good ones. Its hard work, but the traders who have developed profitable systems will tell you it was all worth it. You will also begin to understand why no one wants to give those ideas away, and why the vast majority of systems being sold aren't worth anything. Remember, if it was easy, it wouldn't be worth doing, so keep at it and don't quit.
Best of luck,
Kirk