I can take some fgs, but i would like to know how much it costs and which char is able to do it xd

Depends on how much int and ee you have on your charms.
Rogue's do well with welling- high ee (more choices for your wep), high int armor (more choices/ heavier than robe armor), ee will be the same though between mage/ rogue.
Really depends on what kind of deals you can get, and how well your gear is. You can do very well with a rogue or a mage.

Mana cost has been cut, but the amount of damage has also decreased- just to keep in mind

So rogue or mage is a best choice? Other characters are worse at welling?
And what amount of fg is needed to get good enough stuff ?

Basically yes, for the feeder classes.
You will probably spend ~ 600fg + for somewhat lower end, but yet somewhat successful welling gear.

thanks for help