I have enough materials after MLBing the Rahab weapon, getting all gatcha tickets, getting the first set of SoulP, getting 3 black grimoires and a gold one (grimoires are really expensive!), and all 20 half elixirs to grab one copy of the Rahab eidolon. I was told that there will be some kind of eidolon exchange store so should I get one for exchange purposes in the future?