I wanted to share my opinion about value lists.
For me it would be irrelevant if you decide to remove them because I did not designed my list for personal gain. I help teammates and too many people in the game. They can feel free to ask the reasons why I value one shiny with a certain price in game I can explain each value.
I know that the sale of cheap shinies will continue with or without list of values in the game. Especially ultra rare shinies.
But in particular I think value lists are useful. I remember specifically Hassy past sales when sold Bulbasaur, Skarmory, Houndoom, Vulpix. Quickly and for reasonable prices.
I understand the discomfort of those who want to change their shinies.
But I think the use of indicative values help many people to get an approximate value of their shinies. If shinies are getting cheaper is because most players can not afford big amount of money and new shinies appeared.
One solution in future would be GTL tell us lastest shinies sales here. But of course this would not work with ultra rare shinies and this is where the lists of values are useful. It is true that most experienced players know the price of their own shinies. I do not think it's possible to work in a guide about values in Guide Tavern. Its very complex because many factors involved here and the prices may change for some and not for other people.
On the other hand if values are not desired on shinies in the game would be best to eliminate value lists forever. But I'm sure would be more complicated the sale or exchange of ultra rare shinies.