How to check vitamin levels without a blood test?

Is there any way to check vitamin levels without a blood draw? Honestly, getting blood taken isn't the issue—it's the insane costs. We’re talking $400-$$300 for a single vitamin. If I try to test everything, I'll be out thousands of dollars. I need to get a full picture because my son deals with severe allergies and has been stuck on a super restrictive diet for ages. To make matters worse, doctors here are incredibly stingy with referrals, especially since they’ve already ordered plenty of tests for us. It looks like I'm going to have to shell out a fortune myself.

I've noticed those electrode testing kits you find at drugstores are total garbage. Every time you use one, you get completely different results. That kind of measurement is a known scam.

Are there any other options out there? I’ve read about accredited labs in the US where you can mail in a hair sample to test for minerals, but I haven't found anything similar for vitamins.

What other methods exist for measuring vitamin levels in the body, and where can I actually get this done properly?

Man, I was actually sitting right there in the room during that analysis

I gotta say though, the doc's making some pretty solid points...

Just ask the doc what they can run through a referral. You could check your Vitamin D, magnesium, potassium, sodium, calcium... honestly, just get them to run something.
It’s not all sunshine and rainbows $133. I had my B12 checked and it was $67, and I'm pretty sure my Vitamin D was $67 too.

The labs at my local pharmacy were solid. My magnesium levels were always running low and it was causing me issues. I also think my omega fatty acids were bottoming out since I hate fish and never touched it. I started taking supplements recently, though. Just capsules.

@Drtony, what’s your kid actually allergic to?

I used to be this walking mystery of allergies. My skin was breaking out so bad that some half-baked doctors actually tried telling me I had psoriasis.
Turns out it wasn't anything like that. It was just gluten and a massive Vitamin D deficiency. That was the root of all my "allergies" and basically triggered everything else. Once I got that balanced out, I felt like a completely different person.

Now I live up in the mountains, dealing with the most brutal weather you could possibly imagine. But I'm fine—I can handle it. I spend my time foraging mushrooms and whatever else nature throws at me, even using dandelion greens for salad... that stuff is pure health. I'm constantly discovering new things, like certain mushrooms that help fight cancer.
We really need to get back to basics and eat like our ancestors did. Elderberry juice and bacon are great for the lungs. Mushrooms are loaded with Vitamin D. And d. kopriva? That stuff restores your entire body; you can even make juice out of it.