Value 1 could/should be put in the description of a set, value 2 can be entered by the people adding a set to their collection in the buying value field, value 3 should be like for other catalog items be calculated by value 2s and resolved auction records (and of course be depicted on the page in some way).
But the very first thing should be finally the publishing of set guidelines so the Wild West of set adding is over and everyone can know how a set page is supposed to look like (what information is to be listed etc.).