I agree with the rockwell hardness tester and dust collection whole-heartedly. I'd also say good shop lighting, if you don't already have it. I just bought some high color-rendering-index LED shop lights from American Green Lights, in the process of installing them.
Edit: With respect to grinders, the most highly-recommended ones are here seem to be Travis Wuertz's TW-90, Northridge grinders, and Reeder Product's grinders. I have the Reeder and a bunch of their accessories including their surface grinder attachment, and love their products and their customer service. I can't recommend them enough.