I buy mine on Ebay very inexpensivly. I never bother with the refill crap. Mess to do yourself and when done for you are rarely full from my experience. I got 4 of each color for $14 I think it was and I have 6 colors.That includes the black.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!