It does not make much sense to set a price without doing market research and seeing the prices of competitors. However, if you don't want to deal with it in the first place, the first thing you need to do is calculate the cost.
Once you've made sure you've included all the costs, determining a profit you want to make is the best way forward.
You can price your product or service after you determine a profit based on the target profit you have set in your business plan.