I have some extra Fence Finials leftover from building my fence. These work great on 1/2" PVC as long as you heat the end of the PVC with a heat gun and give it a little crimp. They are on solidly.
Each box contains 100 plastic finials. They are $50.00 per box plus $12.65 flat rate shipping for a total of $62.35 for 100 finials.