My club is hosting a tournament for which we will need a bunch of cheap but sturdy posts. Does anyone have any tips for making posts out of PVC pipe (or any other method of making cheap/sturdy tournament posts).

Dump some cement into a bucket along with the pvc, straighten it up and wait for it to harden. I guess you could use a trash can or whatever container that works

I'd fill them with sand instead of concrete. They'd still be sturdy and heavy, but not completely lethal if someone runs into one. And you can dump the sand out to make them easier to move/store.