House remodel

I own a property where there are 2 dwellings, a 3 bedroom home and a small single bedroom home approximately 450-500 SQFT. The small home was boarded up when i purchased the property several years ago, we decided that we wanted to fix it and rent it out, turns out that all the wood is rotted out and needs to completely replace the entire home. We called Lee County Building department and they told us we needed to have a structural engineer design the plans so we could permit it. We are needing to know what the cost would be for for your engineered plans for permitting the remodel of the house, The house is located at 455 Redlin St. N. Ft. Myers, Fl. 33903, you can reach me at 239-220-1108 Rene Latigo