you know how if you have 2 of the same color of a 4* and you level it to 83, you get 4000 iso instead of the measly 500 for each?
is there a 2 cover of the same color magic level for a 5*? 1000 iso is a ridiculous price to sell a 5* cover for. 
It’s 2000 iso, actually. 
No magic trick for 5’s. The 3&4* trick is related to changing leveling costs after they were part of the game. It precedes 5*s, I believe.
Edit: of course, 2000 is no less ridiculous than 1000 iso.
It would be nice if a 5* bought with CP could be sold for half the CP invested. And to keep it manageable, the same for all vaults, so 10 CP for latest or classic or any other temporary vault
5* cover should sell for 2500 iso and 5cp
I suggest selling them the moment you get them. You’ll be happier with a 4* roster
Not if you ever want to compete in PvE at SCL7 or higher you won’t.
@cooperbigdaddy
If you’re looking for more info about roster growth and leveling, then you should definitely check out / post in Roster and Level Help sub-forum! 
More money, more problems. Less fun. Sell the 5s
I can see getting rid of lower tier 4* as a new player. Making room for better people just makes sense. That said, selling a 5* just sounds like the worst kind of advice. They dont drop nearly as often. Seriously, 15% at best lol.
If you are new to the game, please for the love of god, do not sell a 5* if you pull it! Just in match damage alone, it will speed up your game and get you better rewards, allowing you to progress that much easier.
You want to add yourself to the pile of people people who quit because they feel like they arent making progress, go ahead, sell the one thing that people spend tons of time, energy and money to get. Yeah, have fun with that
Unless you’re buying/rewarding yourself via buy clubs and VIP, it’s not like the 5 star chase is terribly rewarding on its own. Terrible pull rates added to the fact that 5s were designed to be generally unattainable–yet are now required–make a whole lot of stick and not much carrot.