I want to get some new alchool based markers, about 36, and I've been wanting to get some Winsor&Newtoon Brushmarkers, because i love markers with brush-nibs, and because I can't afford that much Copics, but I'm worried about the fact that BrushMarkers aren't refillable. So, I want to ask those of you who used Promarkers/Brushmarkers, how much does one marker last if you use it regularly? Thanks in advance.