The lowest cost for a fully integrated thermal solution is the Parrot Anafi Thermal at $1,900. You may find a used version for less. Do your homework and read the sister Parrot Pilots forum for member's experiences with the Anafi as a whole.
The Anafi thermal has a low resolution FLIR Lepton core. Pros: It is thermal. It is radiometric and give an apparent temperature on screen. It lets you set parameters live in an attempt to obtain true temperatures. It works in FLIR Tools so you can analyze images and gain insight and teach basic thermography.
Cons: It is low resolution. Up close (Within 10 to 15 feet) it works very well for most basic thermal analysis. It will spot wall studs, wet areas, missing insulation. At distance it struggles and the screen will be filled with noise in areas with low temperature differences. For finding people and animals you must be under 100 feet for people and smaller animals even lower.
Examples
My Living Room. Missing insulation on the right, windows in the middle.
Anafi Thermal 10 to 15 feet away.
Now the same area with 640x512 resolution.
Anafi Thermal Solar Panel Array - Bad Cells 10-15 feet above array.
Mavic Enterprise Advanced 640 x 512 resolution from 30 to 40 feet above array.
There are also several vendors that will add different thermal packages to drones. These are not fully integrated solutions and may or may not meet your expectations.
You could easily just buy a thermal sensor on Amazon or eBay and teach him thermography from the ground. This would be extremely cheap for a high resolution camera that FLIR would charge $5,000 and up for. I saw a Chinese 640 resolution camera for $500 on sale before.
