many unable to buy test kids in stores are extending around blocks. >> very from you traded. i've been looking for a test all week, actually, for a few days now. all of the cvss near hi are out, they don't expect any until friday. >> reporter: the demand is so high that cvs, walmart, walgreens are limiting the number of kits that customers can buy. many simply can't find them at all. we searched around. everything is full because of the holidays. >> reporter: compounding the problem, many are confused for what kind of test to get. >> it's confusing what i need to get. >> there's three big categories of tests. within each of thought categories there's a bunch of different manufacturers, a bunch