Joonsus asked "Are there any proven cost effective ways to determine if my invention is worth the money spent for a patent?"
No, there are not.
There are certainly some general indicators that can be used to estimate the probability that an invention may be (a) successfully patented and (b) profitably sold.
A good knowledge of the technology, i.e. familiarity with the industry / technology and actually studying the references found in a prior art search can help you determine if your invention is novel and non-obvious. Of course, your understanding (or your patent practitioner's) is not determinative; the patent office actually makes the decision.
Tools to estimate market size, your potential share of the market, and potential profitability are available. Unfortunately, the estimates are frequently inaccurate; especially when the data inputs (such as advertising budget, manufacturing costs, distribution costs, and overhead) are not accurately known.