OP: Do you buy gas consistently at a high-quality station (eg, Shell, Chevron, BP)? Are you noticing any performance problems?
If it's preventative only, you can get roughly the same effect (which IMHO is only a mental reassurance) by running an injector cleaner (or SeaFoam) through your tank. I've run numerous FI cars over the past 20 years-VERY EARLY on in the switch from carbureted engines, there were problems with injectors clogging, fuel rails varnishing up, etc. But in the past 20 years, injector technology has improved, as has fuel technology.
I would hang on to my $189. You've got as much chance of your injectors failing for electronic or physical reasons in another 100k miles or so as you do them clogging and failing around the same time.