Digital Camera ( as much as possible Sony Mavica ) Air Movers ( 6 to Start ) Dehumidifiers ( 3 to Start ) Moisture Test Meter Moisture Temperature/Test Tool Hydro Sensors Anti-Microbial Chemicals Extractor or Portable Flood Submersible Pump (1)
Equipment Rentals can be an Option but you will pay the Same Price that you will be Charging.
Perhaps preculding all the necessary tools is a thorough understanding of how the tools work. Knowing what your temperature, moisture and Rh/Sh is does you little good if you don't know how to interpret the data.
This looks like a good list. Don't forget about other 'tools' you might need like management software...something that will help you keep bookings, client relationships, and performance tracking running smoothly.