A few years ago, I bought a small Ryobi bench grinder for $40 (I checked, they are still the same price), that has a work light attached. It has paid for itself over at least a dozen times. As soon as a bought it, I could believe I didn't get one years earlier.
My main uses:
If you consider extending the life of tools, plus trips to the store you don't have to make, plus the added safety in using sharp rather than dull implements, it's hard to argue against this having a good impact on the earth and your wallet.
I prefer Ryobi (good quality for DIY), but there are obviously a number of brands that work well. I bought my dad larger one from Harbor Freight a few years ago at Christmas, and its still going strong. It cost about $50.