Interesting question.. In the aviation world everything is tracked as far as serviceable life is concerned, and replaced accordingly. Honestly, $50.00 doesn't seem too bad a price to pay for piece of mind, especially if these are known to fail even after a successful start-up. Its unfortunate that we have no data like this readily available for the automotive world. I would suggest that local driving conditions would also play a role in the longevity of these components.

In the Honda/Acura world this problem also occurred with most of their products made in the late 1980's-1990's, perhaps longer, (I haven't owned any newer than mid-1990's)In this case, the relay was prone to fail on hot days usually at first start-up. I do not recall of it failing after you got the engine to start however. Again, this was only a Honda thing.

Just a few thoughts...