We had to replace the septic system on my in-laws place before we could sell it. It was in Massachusetts, so there were several [link|http://www.marealtor.com/content/title_5.asp|regulations] that came into play.

Make sure to get several estimates. I think the variation was between $12k and $20k for theirs (4 bedrooms, 3 baths). :-(

Best of luck!

Cheers,
Scott.