Given some of the "re-release" prices, I'd be haunting shows looking for one. The odd thing is how kits seem to go in and out as to their easy to find/cheap price availability. They seem to cycle. WNW kits seem to be steady at 5$ off list at the shows around here, and they don't come up too often- maybe 1-3 per show.
I did find a good reference for the Willow: Arawasi Eagle Eye series #2. This covers the k5y1 and -2, and includes well written text, many B&W photos, color illustrations, plans, markings, and a brief rundown of kits. ISBN 978-4-9904647-2-1