Hi Mike,
Check out these two sticky posts if you haven't already done so:
The Estimative Index of Dosing, or No Need for Test Kits
EI light: for those less techy folks
You'll see that you can replace your existing commercial fertilizers with basic compounds that can be found in supermarkets and hardware stores for a fraction of the cost.
You didn't say on what continent you live but test kits can be found at on-line retailers if you google for them. I just entered "kH test kit" in google and I got 1,650,000 hits. Here was the first on the list:
Aquarium Pharmaceuticals Liquid Test Kits - Fresh and Salt Water
That's in North America but I'm sure you could find the same in whatever location you are in. If online shopping is not an option then you might try a local high street pet shop or check yellow pages (if there is such a thing where you live) for "Aquatic Supply" or something similar. In any case, if you study the posts above and if you dose using the EI method as described in the posts referenced, you'll find that you won't really need many of the test kits that are generally advocated. Further investigation will reveal that test kits are notoriously inaccurate, inconsistent and some are absurdly expensive.
Cheers,