If you are not using extra clubs for possibly evolving a club then level them at least halfway before selling. Equipping them and playing 3-4 career mode games should get them to at least level 10 so they are worth 10x more club coins.
Still does not show me where the cub coins accumulate?
Or what I can purchase with them!
Press the level up button when viewing a club stats box. You then see how many coins you have in upper right of screen...
after crafting some boxes, I usually sell the clubs that I will not be using, in turn I receive what I call "Club Coins", question is there is nowhere to purchase anything with these any-longer, what the heck is going on.