The tools should not cost anything much. I carry practically the whole toolkit to do the Annual, change the vac pump, starter motor, etc, in one toolbox.
AIUI a "part F" can be one individual. If you get friendly with one of those, that might be helpful
Avionics (if you understand the stuff) you can do yourself; nobody could ever find out if it is a straight replacement because the serial numbers are never checked, so I wouldn't worry about that. And there are loads of freelance avionics blokes around who will do an avionics test for you for a small fee.
Engine overhauls I wouldn't do unless I was damn good and did it for a living.