Not cheap, see if this helps.
Mine is the Hoot Aerobic System which sanitizes the water and sprays it back on your yard. It was installed in 2005 when I bought this house and cost $6,000. I've heard they are now about $10,000. There is also a yearly maintenance fee of about $200 for someone to check on your system quarterly, but you can also train to do this yourself. Contact your county health department for information.
On average, around $10000 +, in some areas of Western PA.
It can vary widely state to state due to regulations and your presentation soil conditions. My NoNJ black and gray water system with pump replacement was just under 28k.