You can take 2 dusts per day if you have 1 area. You need 300 chaotic soul dusts to get last tier ring of any line, that means 150 days of daily dedication of taking from the npc.
Basically 3 areas is mandatory if you are making the ring, with it being 50 days at least.
For better or worse you will still have to spend GB when botting (in gaia at least), unless you want to keep going back from the save point to the grinding spot when dying. Of course in non-bot situations...too bad.
Personally i feel it is most useful when hunting guild bosses, as accidents happen a lot.