Subdividing a large lot into a flag lot... what are the costs?

[Barrett Anderson]

Hey I am analyzing a deal that has the potential to be subdivided into 2 lots with one of them being a flag lot.  There is an existing house (which is already updated) on the front of the lot.  It is currently .68 acres. The city has said that It can be subdivide with a flag lot.  This deal is in northern Utah county.  My questions are how much should I expect this to cost to subdivide the lot, develop it, and sale the lot? Is it worth the hassle? If I could keep the subdividing and developing cost below $35,000 then this will be a great deal. 

Question 2: how much does having a flag lot behind you devalue a property? Also how much less would a flag lot sale for then a similar lot of the same size.  No comps so far that I can see help me.