These games had severely limited physical releases. Like two copies per store on release date and that was it. Starting with Etrian Odyssey 3 on the DS Atlus really limited the physical releases on this series. That's why EO3 is a $190 game today. All of these games are bound to go to the moon in price in a few months thanks to the eShop closure.
Etrian Odyssey Untold
Etrian Odyssey Untold 2
Etrian Odyssey 4
Etrian Odyssey 5
Etrian Odyssey Nexus