Today I picked up some Budgie Gravel (Hagen) and the box says it has oyster shells in it too. Very small and looks clean - I did see some bottles of grit that looked like fairly large (and kinda dusty) pebbles that were marked for budgies but I wasn't about to get anything that looked like that.
So this evening I first sprinkled a small amount in my open hand. I made sure all birds were in the same room so that they could observe. I offered my hand to Jerry (he's always my taste-tester

) - he leaned in and observed it. He tried 2 bites but was not very enthused. After the two bites he was uninterested. I offered it to Winston next and he wasn't even interested, he looked at it briefly and then flew away. I then offered it to Lulu and she ate 1 bite and then was not interested.
I also put it on a little plate to see if presentation made a difference. No one at any off the plate. I've never claimed that my birds were "normal"

I'll offer it to them again in a few weeks though and see if they take interest then.