The best complete test kit for home use is the CYA test in the Taylor K-2006 kit here which you can get at a good price here and this kit measures CYA down to 30 ppm. Or you can get the equally good TF100 test kit from tftestkits.com here which has 36% more volume of reagents so is equivalently priced and measures the CYA down to 20 ppm.

Or if you already have a good FAS-DPD chlorine test kit that also tests pH, TA, CH and you only need a CYA test, then you can the Taylor K-1721 here for measuring down to 30 ppm or the Taylor K-1720 here for measuring down to 20 ppm.

Richard