Honestly at this point I think my best bet is finding an owner with no mortgage interested in an installment sale.

It has low backwash flow requirements compared with other media like KDF-85.Once properly sized and installed, a KL system should run for 7 years without issues.

. $750 if install central AC and fencing.

I don't know how to investigate this further.Another reason I am inquiring is because we are debating on installing a coin operated washer and dryer on the premise because our water bill for 3 units is over $300 a month and I am guessing a lot of that is because two of the units have washers and dryers.So if they can still do their laundry while giving us a little extra money or at least evening the price out that would be the ultimate solution, but if the shared water would still be an issue then this would obviously become a problem if the tenants electric bills start to go up.

You might have a crack in the foundation and need a french drain installed.

And I have found that the 1970's mud bedded tile installs are solid.  

Now when you rough estimate before seeing the property are you just taking the sqft multiplied by the average cost of installation for say flooring in your area as an example and adding that to the rest of the rehab costs?

I bought the house with a good tenant installed, only to learn that the previous property manager had done something shady with the contract, giving the HHA a contract with rent of about $1,100 then taking it back to the tenant and adding a $300 "maintenance fee".

Installing a new panel?

If it's at all possible (not a bathroom), consider enlarging that one, or installing multiples.Shingles in the gable are good idea, but use a cleat at the bottom to separate them from the siding.