I personally use Salifert. They're a bit expensive and can be hard to find sometimes (they come over on a boat...so sloooow). But, they're pretty accurate, easy to use, and seem to be less of a pain than others. There are some better test kits out (such as Lamotte), but they're either terribly expensive or terribly complicated. I think some other people use Red Sea, but I didn't like it. I use API kits for the basic stuff I don't test much anymore (Ammonia, Nitrite, Nitrate, etc). Once your tank is cycled and stable, you'll quit testing those as much probably and just mainly test alk/ca/mag/pH/salinity/temp. If you're interested in that brand test kit, Marine Solutions usually stocks a nice quantity of their kits. Most of their kits range anywhere from $15 to $30, depending on where you get it and what kit it is.