In Oblivion there are some expensive items but they come from random loot. The most expensive item is mundane ring with 21.000 gold but i think if you are lucky you can find many mundane rings. Unique weapons like Umbra or Goldbrand are somehow expensive but their value was seriously devalued. Umbra's cost fell from 110.000 to 5.500 while Goldbrands cost from 150.000 to 6.500. In Oblivion the best unique weapons were slightly more expensive compared to the best daedric weapons
And we come to Skyrim. As far as i have seen there is absolutely no unique artifact that it is expensive. Most of them cost 1000-2000 gold but its a shame that such an important and legendary artifact like Mehrunes razor costs only 860 gold.On the other hand my epic daedric cuirass with a cool enchantment reaches a cost of 10.000. But since i can make as many daedric cuirasses as i want i dont feel satisfaction in the high cost
Weapons like Mehrunes razor are more artifacts of lore than weapons. They should be much more expensive