The T POST insulator looks nice but the price is ouch!!
We'll have to figure that the op's pole might be 30 feet and he would need at least 5 points to keep the OWL away from the pole.
No rancher would pay that much per insulator for mile of fence.
If you follow the links for any one product you'll see that the quoted price is
typically for a bag of 25 insulators
If they will do the job, it is hardly worthwhile making your own.