Would rotating or flipping disc brake rotors make any sense? Front brakes take the brunt of braking forces - so the front rotor wears faster than the rear. With mechanical disc brakes, the rotor gets pushed in one direction only so wear is also uneven. 

For extreme cheapskates, would rotating your rotors front to back make any sense (assuming same size discs)? 

Would flipping them make any sense (or even be feasible)?
Flipping is not feasible as rotors are directional in design.  You could rotate between wheels ensuring they are in the correct orientation. But I am not sure what you gain, eventually you will need to replace both at once rather than one at a time.  Replacing one at a time could make it easier to spread costs out.

While most cable actuated disc brakes move only one moving piston (note there are some dual sided designs out there, e.g., TRP Spyre) the majority of braking (and friction = wear) happens when the moving piston pushes the rotor to come in contact with the stationary side.  At this point the friction is pretty even on both side.  If you are noticing different wear rates of pads this is likely happening when the brake is not engaged (i.e., rubbing).  As such this is more of a set-up issue rather than an issue with not being able to flip the rotor orientation.

If you are worried about rotor life, you should be using organic pads rather than sintered pads, as these use a softer compound. But I am not sure that this would save you money as you will be replacing the organic pads more frequently.  

That all said, rotors typically take a very long time to wear especially if the use isn't extreme (e.g., commuting/causual riding versus sessioning a world cup downhill run).  If you want to minimized maintenance costs there are other consumables to best focus ones attention on.