Question on Buying and Building on a Vacant Lot

[Jay Velastegui]

I'm currently analyzing a vacant lot in a highly developed city near NYC. The potential deal was brought to my attention by a couple of investors who like myself have zero experience with this. 

The lot is 25x100 and we received a quote from a builder at $85/sq ft. The plans for the building have already been approved by the city. The current owner has decided not to go forward with the build and is looking to unload it and focus on some other areas he's developing in the same city. 

What are other things I should be considering other than comps and making sure I get the lot at the right price? Also any tried and true metrics for determining a good deal with vacant lots would be very useful. 

Thanks!