Once upon a time... In a galaxy too far away it would take to long to list all The fars... There was a place called Cradle...

CE costs 3k CR, you should buy as much as you can. And save it. When CE hits 6 and 7k CR, sell it all. ALL of it. Then as soon as it hits 3k again, buy your profitable CE.

Sidenote-Buy CE with real money when prices are high.

Moral-Buy low sell high