nft are pricey and if you don't live near a store that sells them, you have to pay truck freight as well.
Circular PVC sometimes parts of root don't get water. Can remedy that a bit if you use a heat gun to make the channels flat.
I have used PVC gutters as channels. They have flat bottoms and are cheaper.
only issue wiht those is you need to have a "top" or your water will be an algae brewer.
Im going to use the rain gutter and cover it with foam board of some kind.Easy to cut and lift off to clean.