Customizable guildbank pricer (is there one? is it possable?)

I am looking for a mod that will make adjustments for item prices out of a guild bank

example

Greens = Vendor price + 5%

Blues = vendor price + 50%

Epics = Vendor price + 110%

then reports this price to the user somehow.

If there is a mod out there that already does this, please let me know.

If there is no mod out there, but it is possible, Please let me know.

Thank you in advance for all your help =)