EM items hold no value. They are not TRUE rares
Heck True Rares aren't even True Rares anymore since they were "mass produced" so really there is no such thing as a True Rare.
Rare: marked by unusual quality, merit, or appeal
So a EM item count 10 EM should be worth more then what you call a "True Rare" Two story statue item count 900
As for prices the first posts normally overcharge 500% and then if collectors can get in touch with each other and find out they have all the items they will attempt to set a price together and control the market for the item, thus overcharging you millions upon millions, I almost fell into that a few weeks ago which is why I did not release my sale prices.
BUT if its a really awesome item that does an animation or talks or something special those go for lots and depends on what item it is, color and name.