Walmart does not sell anything other than test strips or OTO based chlorine tests.
My opinion, accuracy aside, is that we should never recommend someone get any type of temporary kit, with one exception. If they already have a TF-100 or k-2006 ordered and If they absolutely need their CYA reading and If they are willing to shell out for something they will likely use once, then and only then would I suggest the HTH 6-way test that has a melamine based CYA test.
It is not a replacement for a proper test kit and we need to make absolutely sure we get that point across. I am rather embarrassed to admit this, but I know that from personal experience. I went two seasons trying to manage my pool using TFPC and a 6-way kit and had minor problems each year. I am such a stickler for getting a proper kit right away because I realize I spent at least as much money in unnecessary bleach purchases as I would have spent on the kit.