The Pool School article does not address the one Walmart sells which is the HTH kits which really only will test 5 things in your pool - Tests for total chlorine, bromine (not used), pH, total alkalinity, total hardness (calcium hardness isn't that big of a deal for vinyl pools unless you have a SWCG), and cyanuric acid/stabilizer
You get what you pay for - the HTH will not test FC, CC and TC separately - it is very limited and will not show shock levels correctly either. It will tell you "up to 100 tests" but keep in mind that is combining all of the items in there, not 100 for each individual item. The CYA only gives you two tests. If you want a kit that does the same number as the TFP kit and all of the different items you need to check, you would have to buy several of the HTH plus some other items that it doesn't include. I went that route for a while until I had a forhead smacking moment when I added up the cost of all of those and the TFP kit was less.