OpenDroneMap or WebODM is as free as it gets, but it will require some knowledge of what you are doing. Self-processing is also very memory intensive. ODM/WebODM works okay in most circumstances and again, it's free. Ground control helps alot, or at the very least some knowledge of how to geo reference an image in GIS software such as
QGIS (also free).
You can plan and autonomously fly your mission with another app such as DroneDeploy or Pix4d (the apps are always free to use, just not their cloud processing). FYI if you are doing this commercially in the USA you are required to obtain a Part 107 certificate.