Is that for a new leech field or does it include the tank as well? 15k is really not that crazy for a working system. I've seen/heard prices go much higher depending on circumstances. Sorry you've got to flush the money so you can flush other things. As someone who has survived the alternative (bad/no septic! as well as tree roots in the main line) I can say piece of mind is money well spent. In my area sewer works out to about 2k/year with average water use, so if a septic is healthy it's adds value to the property vs paying monthly.