Well, as long as your arena is consistent you shouldn't be worrying toooo much at the moment. In my opinion, what you should do is see if you can cut your scout for now, until you expand your arena - that way, you'll be saving money and when you have enough money to expand your arena you can invest and then hopefully your income will increase and then you can use your scouting points again.
And if you want, you can get rid of Costa and get a scrub worth 1-2k, you at least save 1k :)
P.S. Players are sold once you reach 500k in debt.