I personally dont really have a problem with cores anymore, you can get 21 from hawthorne every week arcoss 3 characters, buy 2 everyday from spider + the ones you get by just playing or spidersbounties. If you dont use em like a madman and only infuse when its needed (if it gets a overal light increase of 10) you wont run out as quick. I used about 80cores to get all my 3characters to 700 with the pieces of gear i care about. Iam now at a steady amount of 110cores.