I don't teach Greek, but some thoughts if they're helpful:
The following link has modern Greek onomatopoeia; good to see that _brekekekex_ from Aristophanes _The Frogs_ is still current. Perhaps you could try searching LSJ for the modern terms and finding examples that way?
- http://www.eleceng.adelaide.edu.au/Pers ... nimal.html
Just making a quick check, searching for 'imitate' shows:
- βρεκεκεκέξ to imitate frogs croaking
- γοῖ to imitate pigs grunting
- τήνελλα to imitate the twang iof a guitar string (!)
- καναχή the ring of clash of metal (Soph.)
I have LSJ ripped into a MySQL database, which makes this simple to perform. There's probably something searchable online that would give you these results and more.