One of the up and coming uses of thermal imaging cameras is to mount them on drones or sUAS’s for building inspection, farm inspection, electrical line inspection, safety and security and many many more. To meet this growing demand many manufacturers such as FLIR have created thermal imaging cameras specifically for this these uses. Typically a drone thermal camera is going to be more expensive than normal thermal camera due to its higher resolutions and additional features that it needs to have to be viable. As with other thermal imaging cameras the best drone thermal camera for you is going to depend upon what features you need and how much you want to spend.
Many people have been able to start their own businesses providing many of the above services; and while there is some capital investment this is a rapidly growing industry.
Features - As these thermal cameras are already pretty expensive make sure to only pay for the features that you will need.
Think Ahead - Make sure that you do not just buy a thermal camera for your drone based on what you want to do with it now; think ahead and make sure that it has the features that will not only be adequate now for what you want but also for future projects, jobs etc.
Alternatives - While thermal imaging cameras for drones have many features and are great for enthusiasts, and businesses if you're a hobbyist then it might not be worth it to spend the thousands of dollars. With a little McGuyvering you can rig your Iphone with a Seek Thermal or FLIR ONE thermal imager onto your drone and be able to capture thermal readings. While this will obviously not work for commercial or business applications for hobbyists this can be an inexpensive work around.