That's a beautiful mounting idea. I fear shipping costs might kill the idea of buying online, though. A nice porous clay pot like those would be heavy and fragile!
What about using broken pieces of clay pots? For moisture lovers you could set the piece of clay in a saucer so it could wick the water up.
On a side note for mounting materials, I love the look of cork pieces, and our local nursery Tropiflora sells them fairly reasonably. They also sell online. www.tropiflora.com
The big piece at the top of this pic was only $6 and I could cut about 1/3 of it off for another mount if I needed it. But I like the way it looks. The Brassavola at the bottom is on a hunk of tree fern that I cut from a stump in my garden. I've also mounted a phal on a palm boot, and I'm not entirely sure how that is working yet. Overwatering is a worry here in summer if it rains a lot, but in winter I have to set up a mister on a timer to spray the mounted orchids twice a day if we're out of town.
