I finally bit... Ordered some .3mm (28awg) colored copper craft wire from Etsy.? Shipping included, it was under $10 for 100 meters of wire.? On a per inch basis it is 4x more than a quarter pound of one color from Amazon but 100 meters of wire will wind more? toroids than I am likely to need for the next few years...? (I tried using sharpies to color the wire, but it was hard to see and made a mess on my fingers)