Used Pantone from eBay

Pantone is expensive, and there's no reason you can't use a reference that is a couple years old. You'll miss out on a handful of newer colors, but there are still plenty. They make several versions, and it will depend on your specific work, but the one I recommend is the Color Bridge Coated. It contains all the colors (up to that year) along with RGB, CMYK and Hex/Web breakdowns.

You could also go for a chip book if you need/want the samples. But it won't contain the same breakdown information.