I repaired a unit using these ladies nylon cups, a titch bigger perhaps than you need but they are cheap and available plus you can use the nylons for a whole host of things...other than wearing them, but that's another story
"I found the ping-pong balls used as cups in some projects are too fragile and won't survive strong winds that we sometimes get here at the Great Lakes Shore. The Easter Egg hulls are more reliable, but I could find any in stores at this time (August). However, there are plenty of semi-sphere shaped items in any grocery store. That is what I have found in Walgreens - women's nylon socks packed in almost perfect for my needs plastic cups."
Simple Fix
