opinions on a financial concept

Understanding that there are many different opinions here on this board I am going to ask for some on a concept I have. Please understand that this is a genuine request for objective feedback, I am not soliciting for business.
As background we all know that property has many influences right now and the media has created certain nervousness. I am of the opinion that it is difficult to generalize and that different regions have different circumstances that influence how the property market is positioned or will perform into the future. I am very confident about our region and have planned a small unit development (less than 10) I have found that the market is generally cautious due to negative press and reluctant to commit to pre-sales. As a small family based developer I need pre-sales to secure construction finance and while I have a couple already I need to be creative to meet equity requirements.
So my concept is this.... A purchaser enters into a "Put & Call Option" to purchase one of the apartments. In doing so I offer them 15% discount of the valuation (in this case this equates to around $100K). Of course a bank guarantee would suffice thus reducing cash outlays. The amount of deposit would be around $60K.
Construction would be no more than 12 mths. Before settlement I would "Put" to the buyer that I am selling the subject apartment at normal selling price. In this instance I then pay 20% on the 10% deposit. If you do the math particularly with a bank guarantee you would see the attractiveness of such a return.
Of course there is always the chance of having to settle but I as developer would not wish to give up $100K of my profit under any circumstances. Even if this occurred you have got to ask yourself just how much a property can be devalued?
Such an arrangement secures the required pre-sales and provides investors with a substantial return on minimal outlay.
I am interested in how this is viewed out there in the market and would very much appreciate all opinions.