testing kits....

You can get the CO2 level by plugging in the KH and pH values into a chart, but its not extremely accurate because other factors could affect either the pH or KH (i.e. driftwood).

Are you using pressurized CO2? If so, I'd get a CO2 drop checker that goes by a set KH level to tell you how much CO2 is in the tank (usually set at KH of 4, so that when you have 30ppm of CO2 it turns green which is good...). With DIY CO2 though, you won't get that much CO2. Its best to just use the chart method then, although not always accurate.

Here is Rex's CO2 chart: http://www.rexgrigg.com/co2.pdf.

Most online places have API FW Master Test Kits for <<$20. These are good for pH, high range pH, NH3, NO2, and NO3.

If you use Prime, your NO3 numbers will probably read low (I'm not sure how long that lasts...). Also - if you get a drop checker, the regular pH solution has bromothymol blue in it, so a drop or three is all you need to add to your standard 4DKH solution...