Cost and quality of in house or outsourced sequenc

When is it cost effective to start doing your own sequencing rather than sending samples out to be sequenced? We'd need to purchase hardware, software, reagents and hire a technician. How many sequences would we need to run to have this upfront cost pay for itself? Or are there labs already set up which aren't using their sequencing facilities to full capacity and would like to split resources? How would be find them?