Campbell's Custom Kits, Peck Polymers, Micro X, Aerodyne, FAI supplies, and other freeflight sources have either Esaki silk, or very similar, in a variety of colors. It is near $20 a yard. If you amortize that over the thousand flights you will put on your airplane, it is not much. The Dharma silk I have seen is considerably heavier, but people get good results with it. I don't expect to run out of Esaki silk, some marked $1.95.