From this I took you to mean that you wanted to buy a circuit design (which someone would need to engineer) which had a pcb and a suitable pick and place file (which I’m not sure Fritzing supports) to enable you to buy fully assembled boards from one of the prototype suppliers. That is a fair amount of work and cost and may not be possible with Fritzing. If instead you are looking for a simple circuit with breadboard, schematic and pcb with the files to order the pcb to assemble yourself (which now sounds more like what you want) then Fritzing is likely a good bet (it will generate the necessary files to for a board maker to produce circuit boards for you, just maybe not the files to do automatic assembly). If you post what you want to do we can either suggest a project that can be modified to do the job or perhaps someone will offer to do it for a fee. We usually supply free advise to folks trying to make things here rather than do it as a business, but there may well be people here willing to do that.
Peter