Now the rule is closer to a 2.25 multiplier. These are pretty basic questions, but if the honest answers to them reveal a problem, then you need to rethink the situation. If you have a unique product that people want, then you can charge more for it. Expect to be ripped-off at some point and to have to defend your patent if you have one. You could license your product or contract for its manufacture.
Experienced manufacturers know how to build things the lowest-cost way.
You may even go offshore to get a super low cost. All of these are options to get your product to market at a price that makes sense. This doesn't help if you have your heart set on being a manufacturer. If you are bound and determined to build it yourself, then you need to be diligent in your efforts to find the lowest-cost suppliers and methods.