To reduce driving to the vet clinic to drop off fecal samples I started using mail in services. For me the mail in tests are a bit more expensive than what the vet clinic charges, but the savings in gasoline use and my time offset that difference and more.
But having used three services so far, I wonder about quality. As far as I know, the vet office may even use out-of-house labs too. One service from a major online equestrian shop has a very small sample and no cooling and a paper mailing envelope. Another uses a supplied ice pack and an insulated foil mailer and asks for a sample about 10x the volume.
What is your experience with mail-in services? Are some clearly better than the orhers?