What's the cheapest consumer method for testing my rental home flooring for CH2O (formaldehyde) off-gassing?
$100 for a test kit doesn't seem so bad. Sure it's not as cheap as a radon test kit, but it's a much more specialty item.

I would get one and see what it says, then go from there.

(Looking up that Lumber Liquidaters thing it's not clear to me whether the lumber in question is actually dangerous or just mislabeled. Also, off-gassing is generally worst in the first few months... was any of the flooring installed recently?)