Yeah, totally. I have this really pretty teal fountain pen and it drove me crazy that the only inks I had available were black and blue. If I wanted boring black/blue ink, I could use a boring Bic, yanno?

So I bought teal ink. Writing with that pen is one of the happiest things ever. (purchased from http://www.xfountainpens.com for a total of something like $30? it rocks! the ink itself is "Midnight Sapphire" and is soooo pretty - it's a deep, dark teal so that it still has the legibility feel of blue/black, but it's distinctly prettier)