The1/4" drive hex metric sets are EXPENSIVE unless you know where to find them. I got a 1/4" torque wrench (20 in-lb)from local discount tool store for about $20 but the 1/4" hex metric sockets are harder to find. On regular eBay, they can also be rather expensive but if you go to the eBay Motors you can find the 1/4" hex sets a lot cheaper. I got a metric set that included 1/4" drive with 2-6mm for $20.
Another option is to use the 3/8 size sockets with a reducer to the 1/4 drive. You will want a 1/4" torque wrench. The 3/8" size generally do not go to the lower torque values.