To add to discussion about overhead and profit, I originally wanted to keep the UI simple (hence the one checkbox for total gross margin). Some overhead items, like insurances, etc. could be entered as quotes, but the way you would have to handle O&P is with gross margin. Would you rather see two checkboxes? One for Overhead and one for Profit?
I have a bunch of ideas for the Version 2, if 1 takes off, and I would definitely consider adding that functionality and more and appreciate your input!