This page shows all the five best sell orders for Ayatan Sculptures (and Legendary Cores) on Warframe Market.
The list of orders for each item updates about once every 30 seconds (but not all at the same time). The Endo values for the sculptures are always at their max, independent on the item rank set on Warframe Market.
The Legendary Core is included and is valued at 40,920 Endo, the exact amount of Endo required to max a rank 0 legendary mod. Note however that the Legendary Core has a trade tax of 1 million credits.