Sleip's made a good post..
one thing i'd be carefull with though, are the 3rd demon and sage fairies...
they don't sell that well...
i bought quite a few from catshops for less than 30-50m..... .. better off with tokens
demonic tokens would probably be the best item to merch, if your going that path.. or just farm ec and sell the ec itself
and save the gold, unless you really need coins.. hehe.. you never know when u might need the gold..
e.g... i saved up 50+ gold .... then the morai stuff came out, and i got most of the skills i need fromthe universal chests in the boutique which i blew all my gold on hehe... soooo save them, you never know when you might need them in the future.