In this specific case, my working hypothesis is that the overwhelming majority (if not all) of my choices are of equally mediocre quality, so spending a lot of money to test this is a waste of money.

The "big hardass customer" buys enough product to have a reasonable expectation of effecting change in the suppliers, so running both the experiments suggested by GP, and performing post-mortem analysis of failed components can be expected to steadily improve quality over time.