Cdallas2, the price should not be double, from what I can understand the main $ are in the carbon kevlar fuses.
Sure adding an extra wing, along with changes to fuse formers, etc will sure drive the price up, but I can't see that 2x normal cost is likely?

The classic kit with the wings already sheeted will probably rise a fair bit in cost, as compared to a classic kit of a single winged plane from ZN.

But the Basic kit (cores not sheeted) should not be a whole lot dearer.

Maybe Mark Novak can help here, in estimated costs?