You are right, there aren't really "cookie cutter" builds because there is a LOT of room for customization. When you play a class, you earn CP for that class by killing things, so the more you play that class, the more CP you will have to spend on it. Spending CP for one class will not affect the CP you have/can earn for another class, so simply by leveling class skills, you will not be weakening other classes.
However, when it comes to regular skills, you do have to pay gold for those. Technically there is unlimited gold, but you have to earn that gold through quests and trading. But no, you won't have a magical infinite gold fund ready and waiting for you.
I recommend checking out the Class Guide/Info Forums
here and browsing the Eden Eternal Wiki
. Both of these have a wealth of information waiting for you. You could also ask around in-game and see if you can get some good advice for more experienced players for the classes you like the most.