Colour matching really isn't that difficult. And having correct CMYK values doesn't guarantee you'll end up with a perfect match. All you need is a good colour spectrum/Pantone graphic as a point of reference. Print this graphic on the actual label media you'll be using and then take a sample chip and place it next to the colour area on the printed graphic that matches as close as possible. If you can't find a colour that closely matches the sample chip then find another graphic file (I use several). Once you find your match, use the eyedropper tool to sample that area of the graphic and there you have it... the poor person's alternative to a spectrophotometer. This process needs to be repeated anytime you change the label media, ink or printer.