I decided to start doing them because a friend was diagnosed with a late stage cancer that had very few symptoms and lost his life only months after diagnosis. I guess if I got a positive, my hope would be that my doctor would refer me to a specialist and I'd get a head start and the chance to fight it that my friend never got.

The test is not foolproof and the detection rate for some early stage cancers is quite low. And of course early detection is no promise of a cure. Regardless $800 a year isn't an unreasonable cost for me given I get annual health screenings anyway. My insurance doesn't cover that test but you can use your HSA to pay for it if needed.