You can always make your own. There are lot of Turkish endblown fippleless flutes that started life as offcuts of plumbing pipe or chairleg tubing and were made any random Joe with access to a power drill.

I made a pretty reasonable alto quena in G out of bamboo once - the time it took to voice and tune it hardly made sense in economic terms, but it was technically free.

Somewhere there is a YouTube video about making whistles out of PVC plumbing pipe. With a drill press, bench saw and a sander it's a matter of minutes. Without, you'd better be really keen.