The Fisher is a great pen. I own several and always have a bullet pen in my multitool pouch. However, I find that the PowerTank writes smoother, skips less, smears less than the Fisher. And, the whole pen costs about half of a Fisher refill. I have to do a lot of writing at work and keep a journal in the outdoors, for the last year the PowerTank has been my pen of choice. The only time I switch back to the Fisher is when the temperature drops below 20 degrees or so. At that point the PowerTank starts to clog up and skip.
The cheapest place that I know of to buy the PowerTank is Sam's Club on line. They have them for $1.58 each.