There are two types of buyers. Ship spinners like Zahara Cody/TIGGER and combat pilots like myself. In the case of the Tiamat and Hydra the combat pilot demand is falling off because CCP have purposively made them with only marginal benefits over the standard varieties. This is probably because they have decided the influx of overpowered prize ships is hurting the game. The overall effect of this will be a reducing price.
The only thing holding up the prices in the range of hundreds of billions is the the ship spinners, the Zahara Codys and the TIGGERs, because they do have some nice gold effects that look good when you are ship spinning them on high graphics configuration, and when you undock briefly to see the space lighting reflecting off the gold.
I want to buy a Moracha, please.