I have the Craftsman twin set (standard and metric) and they have the hollow shaft. They go on sale a lot. For the price and convenience, it is a good quality product with easy warranty replacement. I find the 1/4 and the 5/16 drivers get used the most.
They come in handy for plumbing, lawn mowers, and shed repairs.
I fact, I believe that they might be on sale now for 50% off at Sears.
I'll second this. I recently picked up the standard/metric combo set (in the zip up storage case) and they're very nice. They have a little heft to them and feel like they're very well made. Shafts are also hollow on these. At the half off price, they are a steal.
I have also seen and on numerous times admired the Klein ones. Don't get me wrong, they're nice too I'd love to get them but the price point is just a tad high for me (Thanks Home Depot

). I don't see enough quality difference to justify the difference. The fact that c-man gives you a half decent storage case with their set doesn't help Klein's case either.
In all honesty, I have splurged on several occasions to round out my set of Klein screwdrivers, (standard/large/mini/stubbies, etc.) and they are by far my favorites, but screwdrivers get a lot more use than nut drivers. If I used the nut driver as much I probably would have given more serious thought to going with Klein.