Where to Find Larger Perlite

[Mountaineer370]

I'm getting ready to repot a few plants. A couple of them are Paphs that are currently potted in what looks like a combination of some kind of medium bark and large Perlite. I got them from an orchid show a couple months ago. I would like to come up with a very similar mix, but I have had no luck finding Perlite in larger chunks. A couple times, I have ordered what was described as larger Perlite, but upon receipt, it was just fine and dusty, like the stuff you buy in the garden department at the local stores. A hydroponics store near me carries it, but I would have to buy a huge quantity. The Perlite in the pots now appears to be close to 1/2 inch in diameter. I don't think I need it to necessarily be that large (these are pretty small plants), but I'd be happy if I could find something at least 1/4 inch in diameter.

Do any of you have any suggestions for a source of this stuff? Or, alternatively, if you don't think that kind of a mix is the best for small Paphs, I'm open to suggestions.