I tried using coat hanger wire at first since it was what I had on hand. It kind of worked for the Nutball and Flyer, worked for take offs but not landings on the Old Fogey, and couldn't support the weight of the blender.
My LHS finally got in a order of wire and I picked up some. I'm honestly not sure what size it is, It wasn't marked and the bin it was in said it came as bundles of 3 but they were all bundles of 2 and looked bigger than the size the bin said. My calipers put it at just under 2.4mm so it was probably 3/32" which would match the pieces in a bundle as marked on the bins. It's a bit of a pain to work with but makes for MUCH better landing gear than the coat hanger wire. It's the same size as the coat hanger wire (maybe just a hair thinner) but much stiffer and for a 17" piece only 1g heavier.
I'd like to try the next size smaller, this was REALLY tough to bend with just needle nose pliers...but they were still out of the next size down
I'd love to find another source for good landing gear wire though. The LHS is the only place I've found that has suitable wire in the right size but their stock seems unreliable.