Not including the 3D parts, we calculate this at ~$85 per sipper.  This can be $30 cheaper if you don't need the battery, or just use a cheaper battery.  The $30 battery we chose was probably a bit overkill (6600mAh) but we had a bunch around the lab so we used them.  We're also thinking ahead to putting WIFI on this device for data transfer and that will require more battery power.  BOM in the files area as well.