So, I just registered in forums right now in order to suggest this suggestion.
I suggest to make stats for the costumes instead of it being just for a look.
And if anyone say it will not be fair for other players I can say to you :
1. there is a daily giving coins and if players logged in for 7 days in a row he will start getting 35 coins daily and it's really easy.
2. you get 10 coins for first battle win in the day.
In addition to that the players not using all units, they using mostly Miners, Swordwarth, Ranger, Spearton, so they couldn't buy the items for all.
From my side I didn't bought any coins before and I have last Ranger and Miner items and it didn't take long time to get them.