Another option that wasn’t mentioned in the article is a Standby Vacuum System. I lost a vacuum pump in my Cherokee while IFR on the way to OSH one year. I wasn’t in IMC and was able to maneuver around clouds and return home, upon which I ordered and installed a Precise Flight SVS system (now available from ‘The Vacuum Source’). This is the one that taps into your intake manifold to use vacuum from there to spin your gyro instruments, and runs about $650. There are a couple of caveats to using it: It works best when at partial throttle (manifold pressure is lower than atmospheric, therefore more vacuum is generated), and so doesn’t work very well, if at all, at full throttle. It also works best at low altitudes; high altitudes means there isn’t as much difference between manifold pressure and atmosphere. If you’re in a situation where you are at altitude and your gyros are spinning down you can reduce throttle for a period and ‘spin them up’ using this system, but the goal would be to get onto the ground, of course. But it works, and is probably cheaper than many other solutions.