Even beyond that in almost every state you can order your own labs via websites like OwnYourLabs, PrivateMDLabs, RequestATest, etc. OmegaQuant also offers an at home vitamin D test.
If you ask a hundred random people on the street about this, how many would know about it? Transparency is a huge problem here.
And I'd instantly not trust it because providing the service for a nominal fee would be so much less of a money printing scheme than providing the service for a nominal fee, but then once the fee had established trust using that transaction as a sales vector for all kinds of snake oil that's supposedly exactly what you need according to the results. Unfortunately there are many good reasons to burden the medical economy with all these stifling regulations. The quest for the least bad system is a permanent struggle.
I only see a test for each exact vitamin one by one. For instance Vitamin D is $49. Where is the full run-up?