Agree that Salifert is top notch. I think a good value for your money though are the API (Aquarium Pharmaceuticals) test kits. In my experience, they give pretty accurate and consistent results. And they're available just about everywhere at good prices.
The only issue I found with the API tests are that as you get a little further into the hobby and want better resolution on your results, a few of the API kits just don't cut it. For example, the API test kit for nitrates gives you one color for 0.0ppm and another color for 10.0 ppm
. It's pretty tough to know where you're at between those two points. The Salifert kit, on the other hand, can get you a reading down to as low as 0.2 ppm
. Big difference if you're really wanting to get a feel for where your nitrates are. Similar issues with alkalinity.
For me, I use API for ammonia, nitrites, pH, alkalinity, and sometimes calcium. I use Salifert for calcium (most the time), nitrates, magnesium, and phosphates.