Having a good, deep well drilled out here costs a bare minimum of 10-11K-it means drilling through solid limestone, and casing the entire well shaft-you can easily be near 18-20k by the time you are done.
A regular septic system with a tank and drain field starts at about 5k, with an aerobic system costing about 2-4K more, and an ultra-fancy evapo-transpiration system costing up to 18k.
Yeah, but that's hill country, and the pond is probably the water table, so I doubt water is that far down... I know it could be way more, especially if fancy septic is called for, but SOP shouldn't be all that bad. Of course, that all depends upon what the state allows.
All I am getting at is that the requested money isn't very much for the work to be done - The refit on this place, without water and septic, just studs-out remodel (w/ plumbing, insulation, and new wire) and some (partial) T1-11 siding went well over what they are asking for, just in parts... And that's just 1120 ft2... Now I had to replace some floor joists, plate and rim joists too, had to jack up the roof and move a wall, so it was probably a bit more than I am letting on, but still.