Doesnt look like its worth it to play with coins.
1st try = 1 win = 3.4k
2nd try = 4 wins = 14.4k
3rd try = 4 wins = 17.1k
4th try = 4 wins = 28.8k (Walcott in pack)
So I paid 60k for the entry fees and got back 63,7k including match coins (minus boost)
Dont think its worth it to play with coins, pretty much only way how to make your coins back is to win all four. And also the prices of players are very high, so later you wont be able to get this much