I used to base a PPE on the purchase price of the horse and what I intended to use them for.
While I was still horse shopping for my 2nd competition horse, a good friend approached me about selling me her TB gelding. I knew this horse VERY well, and often fox hunted with him and his owner. I was eager to purchase him and since we are such great friends, she offered me a fantastic price!
I was not going to get a PPE on him because I felt I knew him, but she insisted and offered to split the cost 50/50.
The day we met at the vet school, it was discovered he had a melanoma growing behind his eye. Its location rendered it inoperable.
So that PPE saved me a lot of heartache. Now I think twice about them :)