The issue with higher end properties is the traditional formulas are hard to use.

The sellers motivation is very high and willing to give me the property at the cost of the loan payoff, whether that be through a traditional wholesale deal or a subject to

Can the buyer be someone who has a traditional mortgage loan too or is it purely as the title says - only people with a wad of cash.Thanks

At closing you will finance the property, either via some time of mortgage through a traditional lender, private money, hard money lenders, investors, etc.Regardless, unless you are doing some kind of investment offering, the property you are purchasing will be used to secure your funding. 

There are many bank and  non traditional bank lenders who will refi a short term purchase and rehab loan with a permanent vehicle.

I know one of the ways @Brian Gibbons handles this is using the concept of "right of first refusal", rather than a traditional "lease option" for seller financing. 

When you're looking to build you can in theory get lots of "non-traditional" technologies approved.

Found them on the MLS, used traditional bank financing, they are all less than 5 units so we qualified for traditional residential lending, although the down payments were slightly steep between 25-30%, but that has helped cash flow a lot.  

I would also consider seeking traditional financing for this deal with the seller carrying back the down payment on a 5-7 year term.  

Steve, I have traditional lenders who will lend 70% ltv in your current situation with still very low interest rates....