Just successfully refilled the ink cartridge of my printer, the cost different is a kind of crazy, more than 60:1!!!
The ink was purchased online from DealExtreme, now one of my favorite shopping place, and I will always check the price there before heading outside, it's usually cheaper and better yet, it features site-wide free shipping.
There is no trick in re-filling ink, and the instruction inside the package is more than enough. I failed for the first time simply because that ink cartridge was broken originally, the print head was leaking, maybe it's too old or maybe I've handled it improperly before.
I've ordered a re-fill set for the color one as well, will do it later, but it seems the method is a bit different.