For sets it would be nice to have a free shipping checkbox and something to alert buyers that the set has free shipping (kind of along the same alert as "shipping quote required" shows up now). It would also be nice to have a field to enter a shipping amount if you want to set a fixed shipping price for the set.
Comments
Set the specific set to 'force quote', add the free shipping in your 'set description'. If a buyer is interested, he will be forced to ask a quote, you can then provide one at 0.01 $,£,Euro (zero is not possible 'yet').