If you are a Harbor Freight shopper, here's a couple hex key sets that they offer:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37862 $7.99
Sizes: 2, 2.5, 3, 4, 4.5, 5, 5.5, 6, 8, 10mm
Look for it to go on sale every once in a while. I picked up my set for $2.99.
or try this ball-end set
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46531 $9.99
Sizes: 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 10MM