He's put $300k into it and is now in poor health and can't complete it.

Good soils, soil health, proper drainage, climate, etc. would be contributing factors to high value land for agricultural use.

Wipe your cabinets and tub surround with it as well.

Or for health or other 'unforseen' circumstances (triplets!?!).

Apparently, the owner of the land is in bad health, and her heirs are looking to unload it quickly (the land has been for sale for over 10 years). 

If that fails then you'll have to re-locate it somewhere new, so talk with a local septic installer and your health dept and determine what size system you'd need if doing new, then verify that you have the space to do so.

As the Lucas County Health Department (LCHD) has added a new time ticker countdown to the deadline of the Toledo Lead Paint Ordinance compliance date, there are 4 vital reasons why landlords need to get their rentals in Tier 1 inspected as soon as possible.1.

My spouse would continue to work (very easily employable, pretty much anywhere in the English speaking world) for a good salary and, importantly, for health insurance for our family, which should support us adequately.

At one point he decided to purchase individual health plans for himself, my younger brother, and younger sister, rather than bundling them into a policy for the family. 

The bowl under the unfrosted window may be a turn off, also.The full size shower with no tub could be a minus unless the prospective buyer is physically challenged (low / no step-over into the shower).The door out to the balcony looks damaged.My $0.02 ...