I have fluorocarbon tippet and I use it -- sometimes bought as tippet and sometimes bought as fishing line (which is cheaper to buy).

The dollar cost isn't so much a problem for me, what bothers me is the other "cost" in that the stuff never breaks down and although I am not an environmentalist per se, I don't like the idea that I am leaving that stuff in the river or on the river bank somewhere when I snag up on something and have to break my tippet/leader. So, for that reason, I am transitioning back to regular tippet materials. At least, it will break down over time. And, I absolutely hate it when I stumble upon yards and yards of any kind of clear fluoro or monofilament line or leader left on the beach/bank or I pull it up from the bottom attached to my nymphs - Still, if it is mono. it is supposed to break down over time.