I've gotten a few questions about the thing-walled PVC tubing for my PVC Camera mount. I've looked it up, and when you go to the hardware store, if you want to sound smart, ask for the 3/4 inch PVC SDR Schedule 21. You can read more about it here.
Around here, I know Lowe's carries it, but I don't know where else to find it. But Lowe's doesn't carry the flat top caps; only round ones. The person helping me at Lowe's suggested trying a sprinkler supply store or a plumbing specific store.
Hope this helps!