well first off i dont think there is a right or wrong when it comes to tipping.
If you like a product or a service and you can afford to tip- then tip
If you think you got a bad product or service then complain or let them know nicely you expected more.
If you enjoy yourself and enjoy the providers attitude and want to see them again i think tipping is okay even if they are $xxx but its strictly each persons own decision to make.
Some people wont see a provider over $xx.5 because theres none out there worth that but then again i know hobbyist that pay way over $xxxx on some providers and are happy to pay it.
Again its all up to each persons oppinion and some people are more generous than others so dont condem someone for tipping and dont condem them for not tipping.
Just do what you think is right and im sure if a provider gets a tip it will be gratefully taken.