I have looked at this in some detail. Even the most inexpensive Chinese P&P machine is many thousands of dollars (probably over $10K with enough feeders (covering a range of parts) and with vision). They don't run all that fast, the cheap ones, and you seem to have to run them at half speed to get reliable placement and vision slows it further.
The larger professional ones are very heavy and expensive, probably $30-$100K USD and may require 3-phase power. You will also need a decent oven (the batch type ones are not great, especially for Pb-free) and a decent stencil printer. You will have to keep all the various chemicals in stock and fresh.
None of those are really deal killers. The real issue is the setup time, initially for each board and when you change boards, assuming you will be making several products.
Using actual numbers a Youtuber mentioned for his experience and allowing for some improvements with experience I figured the return would be, at best, marginal. You still have to manually inspect the boards and do any necessary rework, you are responsible for controlling the processes, maintaining the machines and ordering spare parts etc., and often there will be parts that have to be manually attached later because they are incompatible with some part of the process (too tall to go through the conveyor oven, through-hole for mechanical or cost reasons etc.)
I strongly suggest you concentrate on your strengths (presumably designing and marketing) and leave the grunt work to someone else. Shop around.
If you are still interested, look carefully at the procedure you need to go through to program a board the first time. It's not just a matter of uploading the file from your PCB program.