0.
NEVER put any money in this game besides your sub.
Minmax everything, farm if needed, Multi-account (two accounts is seriously MORE than double the power cause of synergy) but DO NOT Buy stuff with your cash.
Of course, for the p2w events, it's another story. Some are good but I'm against it but that's not the point here.
I'd suggest coming to ;lnet channel and talk about it early evening eastern time, you'll have a vast amount of opinions and you'll be able to make your own based on them
Ardwen the submitive: [LNet]-GSIV:Ardwen: "not like I was given a choice to opt out of bro mode, bro"