I use the prices on the wiki as an END point because it is based on people /auctioning things... If I'm buying something, I usually get an average of what is on the list in recent history and pull back 2-5%. For example:
http://wiki.project1999.com/Sash_of_the_dragonborn
I was auctioning sash of the dragonborn for 16k. I think I only got 12.7 for it.