I just did a blood spot test for vitamin D. Got the kit from ZRT - took a bit longer to get the results than I would have liked but nothing but it really wasn't out of line - I was just impatient.
ZRT has quite a few tests that can be ordered - both blood spot and saliva and the price is reasonable.
Oh - I found out that my vitamin D is low - 18 (range 30-100; optimal 50-80). My pcp had refused to give me a lab order to get tested.
You can also order a blood spot test - also a saliva test can detect issues. Sometimes better than blood.
ZRT labs is good
google canary club - .. they have tests too.
I just asked this a couple days ago!
HealthCheckUSA is online. Thyroid panel is $85. TSH with free t3 free t4.
Pay online for an 'order form' to bring to their nearest lab. You go there, give blood. They get back to you.
I have not done this yet however.