Looking for artifacts in Sschindylryn

Yath’rin Neer’yl pays an incognito visit to Sschindylryn. She wears an ilythiiri commoner’s outfit and a skull mask to disguise her station and identity. She asks the merchants of the city, skirting the mindflayer one, if they are selling anti-illithid devices such as brain caps or other stronger devices against psionic thought-reading, illusion and psionic attacks.
If pressed why she needs such items, she will claim she needs them for research purposes.
For some reason she is reluctant to use the storage of magic items that the Yath holds, and tells no one of the business she is doing.

(((interested in a DM response if such items might be bought from an npc in Sschindylryn, and if so at what price)))