Thats actually a fairly good idea.
I was reading a few ideas from google, one involved getting a bigger pot, turning it upside down, cutting a hole in it, and then placing the pot inside that. I was warming to that idea, but now you've mentioned using a bigger pot right side up, then glueing that to the concrete tile, I really like that idea.
The pots I am using are 300mm. Im sure I can find the most cheapest 350mm pot ever and glue the base to concrete tiles. Hopefully I can restrict the cost to like $5 per tile/pot setup.
Damn wind in Melbourne, the estate we live in isnt fully finished yet, and I'm not far from a deep gorge, so the wind can whip up from time to time.