Probably the best option for the money is Pix4D. It is local to your computer so there is no internet required to process images. They have an Ag version that is either $1499 per yr or $149 per month and you can purchase a month at a time. There is also a 30 day free trial. When you use the Pix4D Mapper app to fly it will ensure you have proper overlap and image capture for quality processing.

Good luck!

https://pix4d.com/industry/agriculture/