I'm confused about what buckinis are. One shop sold puffed buckwheat and another showed me a grain that looked like little rocks and perhaps too hard to eat raw?

Buckinis are just raw buckwheat. So puffed buckwheat would be raw buckwheat, been puffed. The ones you are looking for are 'raw buckwheat' or 'buckwheat kernels'. Just buy the macro raw buckwheat kernels from Woolies. So just buy the raw buckwheat or you can buy them activated at health food shops (where it's been soaked and dried), doesn't matter. They're crunchy, super yummy. Awesome on nice-cream, really nice on your porridge as well.