At pvc pipe stores.
Seriously though; home renovation stores, or plumbing supply stores.
I would hit your local hardware store.
Anywhere on Earth? I dunno, you didnt give us much to work on. Are you having problems finding PVC pipe? Did you even bother to look yet? Most home improvement stores sell PVC.
As it seems you've never seen the inside of one of those places before, you might like to know PVC pipe is sold in 8 foot lengths. Some store will cut it for you - for a fee.